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THE .NEWER KNOWLEDGE

OF NUTRITION.

THE USE OF FOOD FOR THE PRESERVATION

OF VITALITY AND HEALTH

BY
E. V. McCOLLUM

!.
SCHOOL OP HYGIENE AND PUBLIC HEALTH, THE

JOHNS HOPKINS UNIVERSITY

ILLUSTRATED

1 1

THE MACMILLAN COMPANY

1918

OiCLOCY

UBRAHf

COPTBIOHT, 1918

By the MACMILLAN COMPANY
Set up and electrotyped. Published October, 1918.

PREFACE

The need for knowledge of nutrition was never
greater than at the present time when so large a
part of the energies of the people of Europe and
America are absorbed in the activities of war. The
demoraUzation of agriculture over wide areas, to-
gether with the shortage of tonnage for the trans-
portation of food, have reduced the food supply of
a number of nations to the danger point, and have
cut oflf in great measure the opportimity for securing
the variety which exists in normal times.

The investigations of the last few years have,
fortimately, led to great advancement in our knowl-
edge of what constitutes an adequate diet. Such
knowledge can, if rightly apphed, greatly assist in
enabling us to make use of our food supply in a
manner which will avoid mistakes sufficiently serious
tQ become reflected in a lowering of our standard
of pubUc health. It seems certain that pellagra is
the sequel to the adherence to a faulty diet for such
a period as to materially reduce the powers of re-
sistance of the body to infection, and reasons are
presented in support of the view that there is a

Qft*^!4?50

vi PREFACE

much closer relationship between the character of
the diet and the incidence of tuberculosis than has
hitherto been beUeved. This view is offered in the
present discussion as an invitation to criticism, in
the hope that new data either in support or refuta-
tion of its validity will be presented. If it shall be
definitely proven that faulty diet is the chief factor
in the etiology of this disease, and that pellagra,
is, as the Thompson-McFadden Commission, JobUng
and Peterson and others beUeve, caused by infection,
it will estabUsh that, as the author suggests, large
groups of people are at the present time making
serious errors in the selection of foods. Regardless
of the outcome of future studies relating to the im-
portance of diet to the etiology of these diseases, a
non-technical presentation of the kinds of combina-
tions of our natural foods which induce good or
faulty nutrition in animals, should be of service in
showing the inadequacy of the practice, which is
still in vogue, of regarding calories as the factor of
prime importance in the planning of the diet.

From the data discussed in the following pages it
will be evident that the idea that freedom of choice,
and variety of food sources for the diet will prevent
any faults in the diet from becoming serious, is no
longer tenable, especially if one is willing to admit

PREFACE vii

the existence of many degrees of gradation of mal-
nutrition, not recognizable except in their effects on
the mdividual over a long period of time. The
author recently enjoyed with a friend, a dinner
which consisted of steak, bread made without milk,
butter, potatoes, peas, gravy, a flavored gelatin
dessert and coffee. The meal was appetizing and
satisfying, but such a diet of seeds, tubers and meat
would not promote health in an experimental animal
over a very long period.

The Uterature which has a bearing on the appUca-
tion of modem research to the practical problems
of himian nutrition has become somewhat extensive
and is scattered in technical journals, and is not
readily accessible, or easy to read in proper sequence.
During the present year the author had the pleasure
of presenting an interpretation of this Uterature in
the Thomas Clarence Cutter Lectures at the Harvard
Medical School. BeUeving that the pubUcation of
these lectures would serve to answer many of the
questions which have been asked in numerous letters
from the public, they have been edited and presented
in their present form.

It is a pleasure to acknowledge the author's in-
debtedness to those who have assisted in canying
out the experimental work which made possible the

viii PREFACE

discussion of nutrition offered in this book. Nearly

three thousand feedmg experiments varying in length

from six weeks to four years have been observed.

Special appreciation should be accorded to Miss

Marguerite Davis who assisted with the early work,

in the first two years of which no interpretation of

the cause of success or failure of our experimental ^

animals was possible, and to Miss Nina Simmonds

and Miss Helen T. Parsons for their keen interest 1

and never-faiUng loyalty to the work. -{

E. V. McCOLLUM.

The Johns Hopkins University '^1

School of Hygiene and Public Health,
Baltimore, Md. "]

CONTENTS

CHAPTER PAGE

I. The Biological Method for the Analysis of a

Food-stuff 1

II. Experimental Scurvy and the Dietary Properties

OF Vegetables 34

ni. The Vegetarian Diet 53

IV." The Foods of Animal Origin 69

V. The Diseases Referable to Faulty Diet, or the

So-called "Deficiency Diseases" .....* 83

VE. The Nursing Mother as a Factor of Safety in the

Nutrition of the Suckling 116

VII. Practical Considerations which Should Guide in

"^^ THE Planning of the Diet 130

Introduction to the Legends to the Charts . . . 154

Bibliography 191

Indux 197

^'■'

THE NEWER KNOWLEDGE 0]

THE NEWER
KNOWLEDGE OF NUTRITION

CHAPTER I

THE BIOLOGICAL METHOD FOR THE ANALYSIS OF A

FOOD-STUFF

Our knowledge of nutrition has progressed hand
in hand wi£h the development of the science of
Chemistry. Chemical science gave us the clue to an
understanding of the nature of the food-stuffs and
the changes which take place in digestion, as well
as an appreciation of some of the secrets of the
metabolic processes which take place within the
tissues of the body. Chemistry will continue, as
time goes on, to aid m extendmg our knowledge of
the finer processes of physiology. Nevertheless,
it has been possible for a time to advance very rapidly
in the study of nutrition, from the technical as well
as from the practical standpoint, by a systematic
feeding of simplified diets to animals. The results
were interpreted on the observations as to the abiUty,
or failure, of the animals to develop normally, as
the diets were modified. Progress has resulted in
the past, and will continue in the future to come
from the judicious division of labor between the

2 .: THfi NBWEH KNOWLEDGE OF NUTRITION

study of food problems by chemical methods, and
by animal experimentation. In this brief exposition
of the present situation respecting our knowledge of
foods and nutrition, it is desirable that thfe reader
should appreciate the viewpoint of the investigator,
and should understand the line of reasoning by which
the successive steps in the progress of the last few
years have been attained. A brief historical account
of the steps by which research in this field have been
developed will serve this purpose, and at the same
time, will illustrate the mental processes of a student
engaged in the task of bringing order into a field of
scientific inquiry where before there was no clear
understanding.

A plant structu re^ or an ^nimal body is an exceed-
ingly complex mixture of chemical substances, many
of which are themselves individually as complicated
in their structure as the most complex machine.
The first step in the direction of reaching an under-
standing of the chemistry of the living mass, must
involve the separation and study of the structural
imits of which the tissues are composed. This was,
indeed, the field of activity of many organic and
physiological chemists during the nineteenth century.
The fats and the simpler substances into which they
can be converted as in soap making; the starches and
the simpler sugars, and the manner in which they
are related chemically; the proteins, bodies having
the properties of egg white, the casein of milk, hair,
etc., yet very closely related in their chemical nature,

BIOLOGICAL ANALYSIS OF FOOD-STUFF 3

since they can all be resolved into the same digestion
products in thf^ ft f iiTnt^' ^'^''b^ ^^ ^^ *^® chemical
laboratory, hav^U been carefully studied and with
marked succes^. These and a long list of a thousand
or more relatively simple chemical substances have
been discovered, and isolated in a state of purity from
plant and animal tissues. They have been studied
to determine their special properties, composition
and the tests by means of which they may be recog-
nized and identified.

Through a century of patient labor by many able
men/an imderstanding of the number and character
of simple structural units into which the tissues of
animal or plant can be separated, became reaUzed.
Furthermorq(f certain of these simple bodies could be
recognized as intermediate products on their way
toward being built up into the most highly organized
units of the living tissues; others were shown to be
degradation products resulting from the physiological
activity of the living tissues of the plant or animal.
Through these studies it became estabUshed that the
(body of an animal or the tissues of a plant consists
essentially of: proteins, which are peculiar in that
they contain about sixteen per cent of the element
nitrogen, and are complex in structiu-e; starch-like
substances and sugars, into which the starches can
be easily converted, and fats and a number of closely
related, and, in many respects, similar substances
known collectively as Upoids. With these there are
always associated in the Uving tissues more or less

4 THE NEWER KNOWLEDGE OF NUTRITION

water and a "number of nxlneral salts. Numerous
special varieties of each of these types of substances
became known, and then- less obvious characteristics
were described. Certain substances were foimd to
b€(special products, found only at certam times and
in certain special locaUties,yand these became re-
garded m then- true Ught, as of subordinate interest.
Examples of such are the^lkaloids, quinine, strich-
nine,letc.,Cthe cellulose which serves as skeletal tissue
for tie plant but is not necessary for the animal, and
in the same category belong the waste products of
the life processes of the animal body, most of which
are not found in plant substances. living tissues,
although always associated with nimierous sub-
stances, the exact importance of which could not
be determined, were found to consist essentially of
the proteins, fats, sugars, mineral salts and water^^'
These came to be regarded even as early as 1840, as
the essential and never failing constituents of plant
tissues and were regarded as the essential constituents
of an adequate diet for an animal.

The processes of the digestion of food have excited
the wonderment and have occupied the patient
attention of some of the most earnest students of
physiology and biochemistry. The chemistry of the
fats, and the starches and sugars being simpler, or
rather less complex than that of the proteins, came
to be earUer understood in their essential features.
It was not until toward the close of the nineteenth
centiuy that the nature and extent of protein diges*

BIOLOGICAI. ANALYSIS OF FOOD-STUFF 5

tion became clearly appreciated. Soon after 1900
the researches of Fischerjrevealed the great variation
in the composition of proteins from different sources.^
This discovery intrgduced^into nutrition studies the
idea of quaUty in addition to quantity which had
heretofore seemed satisfactory to students of nutri-
tion. Most proteins were found to be resolved into
eigfiteen simple digestion products called amino-,
acids, and it was foimd that the proportions in which
these were present in the protein molecule varied
greatly in the proteins from different soiu-ces. All
or nearly all of these digestion products appear to
be indispensable constituents of an adequate diet.
All natural foods contain several proteins as the
extensive and valuable studies of Osborne have
shown, ^ and although there are individual proteins
which are entirely lacking in one or more oT the essen-
tial digestion products of proteins, e^ery natural food
appears to contain more or less of each of them.
The proteins of any single food-stuff may be regarded
as biologically complete, but their biological values
differ greatly, depending upon the yield of the
several ajxdno-acids which can be obtained from
them.

Food Analysis. — Since proteins, carbohydrates,
such as starches and sugars, fats and mineral salts
came to be regarded as the essential constituents of
the normal diet, it early became the principal activity
of the investigator of nutrition problems -to analyze
foods of every sort by chemical methods in order to

6 THE NEWER KNOWLEDGE OF NUTRITION

determine their content of what were supposed to
be the only essential food complexes. Pronounced
differences were observed in the composition of the
many substances which serve as food foreman and
animals. Meats, milk, eggs, and a few seeds such
as the pea and bean are very rich in protein, the
cereal grains contain less of this food substance,
whereas the tubers and vegetables, especially in the
fresh condition, contain but very Uttle. Equally
great variations are observable in the water content
of foods, and in their yields of fats and carbohydrates.
One of the great epochs in the development of the
science of nutrition, is that in which Atwater and
his associates examined and tabulated in classified
form the chemical composition of an extensive Ust
of hmnan foods. ^ Following this, similar data were
accimiulated in the Agricultural Experiment Sta-
tions concerning substances used for animal foods.
Up to about 1900 the idea that there was any varia-
tion in the quahty of the proteins from different
sources did not become generally appreciated.

In the Ught of the revelations in the field of nutri-
tion during the last few years, it seems remarkable
that close students of animal nutrition accepted for
so long, without proof, the beUef that the results of a
chemical analysis revealed the dietary values of
food-stuffs.

Disease and Diet. — Restricted diets of monotonous
character have produced, for centuries, diseases in
man in several parts of the world. The only one

BIOLOGICAL ANALYSIS OF FOOI>-STUFF 7

of these which was at all general m the Western
hemisphere was scurvy, a disease which caused much
suffering among sailors in the days of the long sailing
voyages. It was well imderstood that the disease
was the sequel to the consumption of a faulty diet,
composed usually of biscuit and salt meats, and that
prompt recovery resulted from the consumption of
liberal amounts of fresh vegetables and fruits.
Decades passed without any systematic attempt to
determine the cause of the pecuUar value of this
class of foods.

Pellagra was a scourge among the poorest of peas-
ants in parts of Eiu-ope for centuries, and its etiology
has been referred by many to the poor quaUty of the
simple and monotonous diet. This disease was not
observed in America imtil after 1900. Since then
it has been steadily increasing in the Southern States.

Beri-beri is a disease common among the poorest
classes of the Orient, who limit their food supply
principally to poUshed rice and fish. It is remarkable
that not imtil the year 1897 was the first fertile
suggestion made by Eijkman,^ as to the nature of
the dietary fault which was responsible for the
development of this disease.

Man has been sufficiently industrious in most
parts of the world to secm-e for himself a varied
diet, derived from the cereal grains and legumes,
fruits, roots and tubers, meats and certain leaves,
which he found edible. Beginning with the dawn
of the era of his most rapid advance toward achieve-

8 THE NEWER KNOWLEDGE OF NUTRITION .

ment, he has m many parts of the world been the
possessor and protector of flocks and herds, which
provided him with clothing, and a constant supply
of both meat and milk. The importance of this last
item in his food supply we have just now come to
really appreciate. It is in order that it may be fully
appreciated how great are the differences in the
nutritive value of foods of such a composition as to
appear ahke from the results of chemical analysis
that the present accoimt of the investigations of
recent years was prepared.

In the year of 1907 the author began the study of
nutrition problems at the Wisconsin Experiment
Station.^ An inspection of the Uterature which re-
lated to nutrition at that time disclosed the fact that
the diet was supposed to consist essentially of pro-
tein, carbohydrates and fats, and a suitable amount
of several mineral salts. ] There were in the Uterature
two papers which were highly suggestive that a new
era was about to dawn in this field of research.
Henriques and Hansen,^ beheving that gUadin, one
of the proteins of wheat, was free from the amino-
acid lysine, had made up a diet of purified gUadin,
carbohydrate, fats and mineral salts, and had at-
tempted to nourish on this food mixture, animals
whose growth was complete. It was reported that
rats had been kept in a state of nitrogen equihbrium,
and even retention of nitrogen (protein) was reported
diuing an experimental period covering nearly a
month. In most of their trials the animials failed

BIOLOGICAL ANALYSIS OF FOOD-STUFF 9

steadily from the time they were confined to food
of this character.

Willcock and Hopkins ^ had conducted experiments
with similar food mixtures, composed of carefully
purified food-stuffs in which all the constituents
were known. When the protein of the diet consisted
solely of zein, from maize, the mice Hved but a few
days. When to this food the amino-acid trypto-
phane, which is not obtained on the digestion of
zein, was added to the diet, the animals Uved dis-
tinctly longer than without this addition. All ex-
perimental work with such diets indicated that they
were imable to support well-being in a young animal
during growth over a prolonged period. It was an
interest in these results, and a desire to know why
such food mixtures, which comphed with all the re-
quirements of the chemist and the dietitian, failed
to properly nourish an animal that led to the decision
that the study of nutrition offered a promising field
of activity.

At the Wisconsin Experiment Station there was in
progress at that time an experiment which greatly
strengthened the author's conviction that the most
profitable point of attack for the study of the prob-
lems of nutrition, lay in the study of greatly sim-
plified diets so made up that every component should
be known. It seemed that, employing such diets,
and by the systematic addition of one or more purified
substances known to be found in natural foods, or in
animal tissues, it should be possible to arrive at the

10 THE NEWER KNOWLEDGE OF NUTRITION

solution of the problem of just what chemical com-
plexes are necessary in the diet of the higher ani-
mals.

The above experiment was based upon earUer
work by Professor S. M. Babcock, and was suggested
by him, and carried out at first by Professors Hart
and Humphrey, and later with the cooperation of
Mr. Steenbock and the author.^ In this experiment
the object was to determine whether rations, so made
up as to be alike, in so far as could be determined by
chemical analysis, but derived each from a single
plant, would prove to be of the same value for growth
and the maintenance of vigor in cattle.

The ration employed for one group of animals was
derived solely from the wheat plant, and 4Consisted
of wheat, wheat gluten and wheat straw; for a second
group the ration consisted entirely of com plant
products, and included the com kernel, com gluten,
a by-product of the, com starch industry, and the
leaves and stalks of the com plant (com stover);
the third group derived their ration solely from the
oat plant, being fed entirely upon rolled oats and
oat straw. There was a fourth group which it was
supposed would serve as controls, which was fed a
ration having the same chemical composition, but
derived from about equal parts of wheat, com and
oat products.

The animals employed were young heifer calves
weighing about 350 pounds, and were as nearly
comparable in size and vigor as could be secured.

BIOLOGICAL ANALYSIS OF FOOD-STUFF 11

They Were restricted absolutely to the experimental
diets, and were well cared for. They were given all
the salt (NaCl) they cared to eat, and were allowed
to exercise in an open lot free from vegetation. Their
behavior during growth, and in performing the f uno-
tions of reproduction were extremely interesting.
All groups at6 practically the same amount of feed,
and ' digestion tests showed that there was no^iif^
ference in the digestibility of the three rations.

It was not until the animals had been confined to
their experimental rations for a year or more that
distinct differentiation in their appearance was easily
observable. The com fed group were sleek and fine
and were evidently in an excellent state of nutrition.
In marked contrast stood the wheat fed group.
These animals were rough coated and gaunt in
appearance and small of girth as compared with
those fed the corn plant ration. The weights of
the two groups did not differ m a significant degree.
The groups fed the oat plant ration and the mixture
of the three plants, leaf and seed, stood intermediate
between the two lots just described. The assumpti6n
that the animals receiving the mixture of products
would do better than any of the others, and thus
serve as the standard group for controls was not
reahzed. The com fed animals were at all times in
a better state of nutrition than were those receiving
the greater variety of food materials.

The reproduction records of these animals are of
special interest. The com fed heifers invariably

12 THE NEWER KNOWLEDGE OF NUTRITION

carried their young the full term, and the young
showed remarkable vigor. All were normal in size
and were able to stand and suck within an hour
after birth as is the rule with vigorous calves. All
lived and developed in a normal manner. The young
of the wheat fed mothers were the reverse in all
respects. All were bom three to four weeks too
soon, and all were small and weighed on an average
forty-six poimds, whereas the young of the com fed
animals weighed 73 to 75 poimds each. This weight
is normal for new-bom calves. The yoimg were
either dead when bom or died within a few hours.
The young of the mothers which had been grown on
the oat plant were almost as large as those from the
com fed mothers, the average weight being 71
poimds. All of them produced their calves about
two weeks too soon. One of the four was bom dead,
two were very weak and died within a day or two
after birth, the fourth was weak, but with care it
was kept aUve. The young of the cows fed the
mixture of the three plants were weak' in most cases,
and one was bom dead and one Uved but six days.
The mothers were kept on their experimental rations,
and the following year they repeated in all essential
details the reproduction records observed in the first
gestation period.

Records were kept of the milk production during
the first thirty days of the first lactation period. The
average production per day by each individual in
the corn-fed lot was 24.03 pounds; for the wheat- fed

BIOLOGICAL ANALYSIS OF FOOD-STUFF 13

animals 8.04 pounds, and for the oat-fed animals
19.38 pounds. Those fed the mixture of the three
plants produced 19.82 pounds of milk per cow per
day during the first thirty days. In the second lacta-
tion period the figures for milk production were
28.0; 16.1; 30.1; 21.3 poimds, respectively, per day
during the first thirty days.

Through autopsy and analysis of tissues of the
young, and analysis of the feces and urines of the
animals in the several groups, an elaborate attempt
was naade to solve the problem of the cause of the
marked differentiation of the animals fed these
restricted diets. Interesting data were secured
which showed marked differences in the character
of the fat in the milk of cows from the different lots,
and the observation was made that the urines of the
wheat fed animals were invariably distinctly acid
in reaction, whereas those from the other lots were
alkaline or neutral to litmus indicator. It was not
possible by any means known to physiological chem-
istry, to obtain a clue to the cause of the pronounced
differences in the physiological well-being of the
different lots of cows. This experiment confirmed
the author's conviction that the only way in which
the problems of nutrition could ever be solved, would
be to solve the problem of the successful feeding of
the most simplified diets possible. If this were
accomplished it would be possible to proceed from
the simple to the complex diets employed in prac-
tical nutrition, ascertaining the nature of the dietary

14 THE NEWER KNOWLEDGE OF NUTRITION

faults in each of the natural foods, singly, the seed
alone, and the leaf alone before attempting to inter-
pret the cause of malnutrition in animals fed the
more complex mixtures.

Such an undertaking as that just described, viz.,
the solution of the problem of why animals do not
thrive on a diet of purified protein, starch, sugars,
fats and inorganic salts which contained all the
elements known to be left, as ash, on the incineration
of an animal body, necessitated the employment of
small laboratory animals. Thi^ was true for several
reasons: First, because it is difficult and laborious
to prepare isolated and purified food substances in
sufficient amoimts for the conduct of feeding experi-
ments; second, it is both necessary and desirable to
shorten the length of the experiments as much as
possible, consistent with obtaining data regarding
growth and reproduction, in order that data may
accumulate sufficiently fast to make progress reason-
ably rapid. The domestic rat seemed tabe the most
suitable animal, and accordingly it was selected.
The rat has a gestation period of but 21 days, and
the young are ready to wean at the age of ^5 days.
The female usually produces her first Utter of young
at the age of about 120 days, and will as a rule have
five litters by the time she reaches the age of four-
teen months, which age marks the end of her fertiUty.
The span of fife of a rat which is well noin^ished is
about 36 months. When such an animal is employed,
it is possible to accompHsh within a relatively short

BIOLOGICAL ANALYSIS OF FOOD-STUFF 15

time, the accumulation of data regarding growth
and reproduction which it would take years to secure
with domestic animals of large size, long period of
gestation and long span of life.

A sufficient nimiher of comparable experiments
have now been conducted with several species of
animals to make it appear certain that the chemical
requirements of one species are the same as that of
another among all the higher animals. The require-
ments with respect to the physical properties of the
food vary greatly. The rumiuants must have bulky
food with the right consistency, whereas the omnivora
(man, pig, rat, etc.), cannot, because of the nature
of their digestive tracts, consume enough of such
foods as leaves and coarse vegetables, to meet their
energy requirements.

The early efforts to nourish young rats on diets
composed of purified proteins, carbohydrates, fats
and mineral salts, confirmed the results of the earlier
investigators. The animals Uved no longer on such
food mixtures, than when allowed to fast. The
rations employed were of such a character that the
most thorough chemical analysis could reveal no
reason why they should not adequately nourish an
animal. It seemed obvious that there was some-
thing lacking from such mixtures which is indis-
pensable for the nutrition of an animal, and a system-
atic effort was made during the years that followed
to discover the cause of failiu-e of animals to develop
on diets of purified and isolated food-stufifs. It was

16 THE NEWER KNOWLEDGE OF NUTRITION

not until 1912 that light began to be shed upon the
problem.

The diet which was most in use at that time con-
sisted of purified casein to the extent of about 18
per cent, lactose 20 per cent (supposed to be pure),
about 5 per cent of some fat, together with a salt
mixture which was miade up in imitation of the min-
eral content of milk, and the remainder of starch to
make 100 per cent.^ This food mixture was sup-
posed to be composed of materials sufficiently pure
to comply with the requirements of such work;
that is, they were supposed to contain too httle of
any impiu-ities which would in any way influence
the results. With this diet the interesting observa-
tion was made that growth could be secured when the
fat in the food mixture wa^ butter fat, whereas no growth
could be secured when the butter fat was replaced by
lard, olive oil or other vegetable oils. Egg yolk fats
were next tried and were found to induce growth in
the same manner as butter fat. It was definitely
estabhshed that, contrary to the past beUefs, the
fats are not all of the same dietary value. Certain
fats contain some substance which is not dispensable
from the diet, whereas other fats do not contain the
dietary essential in question.

The portion of the food mixture other than !at,
appeared to contain only substances of known com-
position, i. e.y protein, carbohydrate and inorganic
salts, and for a time it appeared that the imknown
substance in butter fat was the only element, of

BIOLOGICAL ANALYSIS OF FOOD-STUFF 17

mystery in the diet. The lactose or milk sugar was
carefully examined as to its purity and was judged
to be sufficiently pure to be satisfactory for such
experimental work, since it was practically free from
nitrogen. The tentative conclusion was reached
that the essential factors in an adequate diet included
one substance or a group of substances which had
not been appreciated in the past, and that these,
if there should be more than one, were associated
with certain fats but not with all.

This observation was in harmony with the pub-
lished work of Stepp ^ which had appeared in 1909.
Stepp observed that grown mice were satisfactorily
nourished by a bread which was made with milk,
but that early failure and death followed when the
animals were fed the same bread which had been
previously extracted with alcohol. When the sub-
stances extracted from the bread by alcohol were
replaced, the bread was again rendered efficient for
the maintenance of life and health. He demonstrated
in other experiments that the breads could be ex-
tracted with ether or with chloroform without re-
moving the substance which was soluble in alcohol,
and without which the animals steadily failed.
Stepp considered the unknown substance or sub-
stahces with which he was deaUng in his feeding work,
as belonging to the not well defined group of sub-
stances generally called Upoids. This group includes
fats and related substances more complex in char-
acter, some of which contain the elements, phos-

18 THE NEWER KNOWLEDGE OF NUTRITION

phorous and nitrogen. Stepp was not able to secure
with any known lipoid, the effects which resulted
frorii the administration of the alcohol-soluble por-
tion of his milk bread.

A new viewpoint was suggested by F. G. Hopkins
of Cambridge, England, in 1912.^^ He had as early
as 1906 conducted experiments in the feeding of mix-
tures of purified protein, carbohydrate, fats and
mineral salts and was aware of the fact that neither
maintenance of body weight, nor growth could be
secured with such diets. He then tried the addition
of such amounts of milk as would furnish 4 per cent
of the total dry matter of the food mixture and ob-
served that growth could proceed when such milk
additions were made. Hopkins suggested the exist-
ence of certain unidentified food substances which
were supplied by the milk and to these he gave the
name ''accessory" articles of the diet.

Attention has been called to the fact that Eijk-
man, a student of the disease, beri-beri, made the
discovery in 1897 that pigeons fed solely upon pol-
ished rice, develop usually within three or four weeks,
a state of paralysis which is called polyneuritis, and
is analogous to beri-beri in man. He found that
when the birds were given the entire rice kernel, or
unpohshed rice the disease did not develop. It was
found, furthermore, that the administration of rice pol-
ishings to pigeons suffering from polyneuritis, caused
prompt relief of their symptoms. Eijkman's ob-
servations attracted Uttle attention until 1911, when

BIOLOGICAL ANALYSIS OF FOOD-STUFF 19

Funk took up the study of beri-beri, and made an
elaborate attempt to isolate and study the '^ curative ''
substance in rice poUshings.^i Fraser and Stanton
had, however, in 1907, employed alcohoUc extracts
of rice poUshings for the relief of experimental
polyneuritis.12 In the work of these investigators
the erroneous assumption seems to have prevailed
that the process of poUshing consists essentially of
the removal of the outer covering, or bran layer of
the rice kernel. As a matter of fact the rice germ
is in a very exposed position, and is easily rubbed
oflf during the process of. polishing. As was later
shown by McCoUum and Davis, for the wheat
kernel, the germ is a very different thing from the
seed from the dietary standpoint. ^^ The reason for
this will be made clear later.

The studies of Eijkman, Hopkins, Fraser and
Stanton and Funk, referred to above, clearly sug-
gested that there was reqmred in the diet something
other than protein, carbohydrate, fats and inorganic
salts. When McCollum and Davis succeeded in
securing growth in young rats fed upon, a mixture of
'^purified'' food-stuflfs, when the mixture contained
butter fat, but no growth when vegetable fats or
the body fats of animals were substituted, it appeared
to them that the only element of mystery in the diet
was that associated with certain fats. This could
not at first be harmonized with the observation of
Funk, namely, that butter fat had no favorable
influence on pigeons which were suffering from ex-

20 THE NEWER KNOWLEDGE OF NUTRITION

periinental beri-beri.^^ His studies seemed to in-
dicate that there is necessary in the normal diet at
least one other substance, the absence of which
brought on the attack of polyneuritis. Later experi-
ments by McCoUum and Davis cleared up the prob-
lem, but not without a considerable amount of
experimenting and delay.

McCoUimi and Davis arrived at the conclusion
that aside from the long recognized constituents of
the normal diet, there is some unknown substance in
butter fat which must Ukewise be furnished in the
food, and began a systematic investigation of the
problem of why a young animal cannot grow when
restricted to a single grain such as wheat, maize
(com), oats, peas, beans, etc. They had tried many
times to limit young rats to whole wheat, or other
grain as their sole food, and had found that they
not only failed to grow, but would not Uve many
weeks. Chemical analysis shows the cereal grains
to contain all the essential food substances, for which
we know how to analyze, viz : proteins, starch, sugar,
fats and all the mineral salts which occur in the body
of an animal.

It was .reasoned that, since all the dietary essen-
tials, except possibly the one which is not present in
vegetable fats, are certainly present in the wheat
kernel, the faults in the latter must depend upon a
lack of the unknown substance contained in butter
fat, or on the quaUty of some one or more of the well
recognized constituents of the diet. It seemed

BIOLOGICAL ANALYSIS OF FOOD-STUFF 21

possible to discover by means of a systematic series
of feeding experiments in which the quality of the
seed should be improved with respect to one dietary
factor at a time, which factor was interfering with
growth. Accordingly they fed wheat in the following
combinations, and with the results noted:

(1) Wheat alone no growth, short life.

(2) Wheat plus purified protein no growth, short life.

(3) Wheat plus a salt mixture which gave it a mineral content

similar to that of milk very little growth.

(4) Wheat plus a growth promoting fat (butter-fat)

no growth.

From these results it seemed apparent that either
their working hypothesis regarding the factors which
are necessary in an adequate diet, must be wrong,
or there must be more than a single dietary factor
of poor quality, and jointly responsible for the poor
nutrition of the animals. In order to test this theory
they carried out another series of feeding experiments,
in which wheat was fed, supplemented with two
purified food additions.

(5) Wheat plus protein, plus the salt mixture. Good

growth for a time. Few
or no young. Short life.

(6) Wheat plus protein, plus a growth-promoting fat (butter-

fat) No growth. Short life.

(7) Wheat plus the salt mixture, plus the growth-promoting fat,

(butter-fat) Fair growth for a time. Few

or no young. Short life.

22 THE NEWER KNOWLEDGE OF NUTRITION

The behavior of the animals fed wheat with two
purified food additions was highly suggestive that
there are three dietary factors of poor quaUty in
the wheat kernel. This was demonstrated to be
true by a feeding trial in which wheat was fed with
three purified food additions:

(8) Wheat plus protein, plus the salt mixture, plus a growth-
promoting fat (butter-fat) Good growth, normal

number of young, good
success in rearing young ;
life approximately the
normal span.

McCollum and Davis were, in 1912, more than
ever convinced that the only element of mystery in
the normal diet was the unidentified substance in
butter fat, for with the improvement of three dietary-
factors wheat became a satisfactory food for the
nutrition of an animal during growth and for the
support of all the functions of reproduction and
rearing of young.

This series of experiments brought to fight two
new viewpoints in animal nutrition, one of which was,
that the inorganic content of the wheat kernel, although
it furnishes all the necessary elements, does not contofin
enough of certain of these to meet the requirements of a
young animal during the growing period. It is true
that some years earlier Henry, ^^ had called at-
tention to the deficiency of the com kernel in ash
constituents, and had in some of his experiments

BIOLCXJICAL ANALYSIS OF FOOD-STUFF 23

added wood ashes to the diet, with noticeable im-
provement in the well-being of the animals. The
fact that seeds such as wheat fail to supply enough
of any of -the essential inorganic elements was not
geneially appreciated and was given but Uttle at-
tention in works on nutrition. Later, work by Mc-
Collum and Simmonds, demonstrated that the de-
ficiency in mineral elements in wheat and other
seeds is limited to three elements, calcim, sodium
and chlorine.

A second new viewpoint brought out by these ex-
periments was the fact that the wheat kernel is indeed
too poor in its content of the unidentified substance
which butter fat contains ^ to satisfactorily nourish an
animal over a long period of time.

It has already been mentioned that the studies of
Kossel, Fischer and of Osborne, had made it clear
that there should exist very pronounced differences
in the value of the proteins from different sources.
The proteins were prepared in a state of relative
purity and were digested in the laboratory by means
of acids, and were analyzed by the methods of
Fischer and of Kossel. Certain of the eighteen di-
gestion products, the amino-acids, were determined
quantitatively so far as the methods would permit.
Although the methods were never perfected so as to
give results which were approximately quantitative,
except in the case of less than a third of the amino-
aci(£ which were known to be formed in the di-
gestion of proteins, it was shown in the case of these

24 THE NEWER KNOWLEDGE OF NUTRITION

few that there were very great variations in the pro-
portions among them in the mixture obtained from
proteins from different som-ces. Thus the proteins
of the muscle tissues of several species of animals
were shown to yield between 12 and 14 per cent of
glutamic acid, one of the digestion products obtained
from practically all proteins. The same amino-acid
is present in the two principal proteins of the wheat
kernel to the extent of about 40 per cent of the
total protein. These two proteins together make
about 85 per cent of the total protein of the wheat
kernel. Other equally great differences were shown
to exist in the composition of proteins of om* common
food-stuffs and those of the tissue proteins which
are formed during growth.

A good illustration of the problems which the
animal meets in its protein nutrition, may be had by
comparing the digestion products of the protein
molecule to the letters of the alphabet. The pro-
teins of the food and of the tissues are made up
of the same letters arranged in different orders and
present in different proportions. In growth the
animal takes as food, proteins which are very unlike
those of its tissues, digests these into the simple com-
plexes, the amino-acids, and then, after absorbing
these, puts together the fragments in new order,
and in new proportions to form the tissue proteins.

If the muscle tissue of an animal be likened to a
block of printer's type so arranged as to prmt the
rhyme beginning ''Jack Spratt, who could eat no

BIOLOGICAL ANALYSIS OF FOOD-STUFF 26

fat, and his wife could eat no lean/' the proteins of
which the muscle consists are represented by the
individual words, and the digestion products of the
proteins by the letters of which the words consist.
Now if the animal could take in its food proteins
which correspond to a block of type which would
print the jingle beginning: ^' Peter Piper picked a
peck of pickled peppers,'' it is easy to understand
that when the proteins of the food are resolved to
their constituent letters, and an effort made to form
the body proteins of the new and different type
from the letters supplied by the food, the trans-
formation cannot be made. In setting up the first
line, ''Jack Spratt could eat no fat and his wife
could eat no lean," we need foiir of the letter t, but
the food proteins contain but one. The first line of
the Jack Spratt rhyme, which represents the muscle
proteins, requires but one letter p, whereas the food
proteins represented by the Peter Piper rhyme
yield nine in the first line. The first Une of the
Jack Spratt rhyme contains the letters j and n,
whereas the Peter Piper rhyme contains none, so
that even with the entire stanza:

Peter Piper picked a peck of pickled peppers
If Peter Piper picked a peck of pickled peppers,
Where's the peck of pickled peppers,
That Peter Piper picked?

it is not possible to reproduce even the first Une of
the Jack Spratt rhyme, and in order that growth

26 THE NEWER KNOWLEDGE OF NUTRITION

might become possible, it would be necessary to
take proteins of another character, which would
supply the missing letters.

Such a comparison between food proteins and
tissue proteins gives a good illustration of the kind
of problem which the animal meets in its protein
nutrition. The most conspicuous protein of the corn
kernel (zein) is wholly lacking in three of the amino-
acids of digestion products which are obtainable
from most tissue proteins. In accord with what we
should expect on theoretical grounds, this protein
is, when taken as the sole source of amino-acids, not
capable of supporting growth, or of maintaining an
animal in body weights This illustration shows how
we may have excellent, good or poor food proteins
for the formation of body protems in growth.

The investigations described above, the object of
which was to find the (Jause of the failure of an
animal to grow when restricted to wheat as its sole
source of nutriment, were carried out in 1912, the
year following the publication of the first work by
Funk on polynemitis. In the same year Hop-
king called attention to the remarkable effects pro-
duced by the addition of small amounts of milk to
diets composed of purified food-stuff s. The '^ vita-
mine" hypothesis had just been formulated by
Funk.^^ McCoUumand Davis were, therefore, aware
of the relation of a diet of polished rice to experi-
mental beri-beri. They beUeved, in the light of
their experiences with the diet of piuified protein,

BIOLOGICAL ANALYSIS OF FOOD-STUFF 27

carbohydrate, fats and inorganic salts, Which, they
observed, was capable of inducing growth when cer-
tain fats were supplied, but not when others were
substituted, and the further fact that wheat could
be supplemented by purified protein, a growth-
promoting fat, and a suitable salt mixture, i. e, with
food-stuffs of known character, that there was but
a single unidentified substance necessary in the diet.
They decided to next apply to polished rice the
same procedure which had shown so clearly the
nature of the dietary deficiencies of wheat. Rice,
they reasoned, could be nothing less than a mixture
of proteins, starch, traces of fat, and a mixture of
inorganic salts, similar to that contained in wheat,
but smaller in amount. It should, therefore, be
supplemented with a suitable salt mixture, a purified
protein, and a growth-promoting fat, so as to in-
duce growth and maintain animals for a long time
in a state of health. This seemed to be a necessary*
conclusion, since they had secured growth and well-
being in animals fed strictly upon a mixture of puri-
fied protein (casein), starch, milk-sugar, butter fat
and a naixture of inorganic salts of suitable com-
position.

It was a great surprise to McColIimi and Davis
to find that polished rice, even when supplemented
with the purified protein, casein, butter fat and a
salt mixture properly constituted, failed utterly to
induce any growth in young rats.^^ Not only did
they fail to grow, but in the course of a few weeks

28 THE NEWER KNOWLEDGE OF NUTRITION

they developeki in some cases a state of paralysis
which was suggestive of polyneuritis. Here was an
apparent contradiction. The polished rice could be
nothing less than a mixture of protein, carbohydrate
and salts. The only difference between this and the
mixture of supposedly purij&ed food-stuffs with which
they had achieved success was in the 20 per cent of
milk sugar which the latter contained. •" It was,
therefore, decided to repeat the experiments with
the latter mixture, • with the milk sugar replaced by
starch. It was foimd that this change in the com-
position of the food mixture made the difference be-
tween success and failure. No growth could be se-
cured when the milk sugar was omitted. Later
experiments showed that if milk sugar was suf-
ficiently purified by repeated crystalUzation it was
no longer effective in inducuig growth when added
to the purified food mixture-, whereas the water from
which the sugar had been crystalHzed would, when
evaporated upon the food mixture, render it capable
of inducing growth. This made it evident that there
is indeed a second dietary essential, of which an
animal needs but a very small amount, but which
is absolutely necessary for both growth in the young
and the maintenance of health in the adult.

Further experiments were then conducted to find
whether this unidentified substance which was being
added accidentally as an impurity in the milk sugar,
was the same as the substance which Fraser and
Stanton and Fimk were dealing with in their studies

BIOLCX^ICAL ANALYSIS OF FOOD-STUFF 29

of beri-beri. It was found that pigeons which had
developed beri-beri as the result of being fed ex-
clusively upon polished rice, could be temporarily
"cured" with any preparation which would, when
added to the diet of purified food-stuffs, contaiiling
a growth-promoting fat, cause animals to grow.

Following the method introduced by Fraser and
Stanton, McCollum and Davis, ^* next employed
alcoholic extracts of various natural foods, adding
the alcohol soluble matter to the standard mixture
of purified protein (casein), starch (dextrinized) ,
salts and butter fat, and soon became convinced
that the substance which reUeves the condition of
polyneuritis in pigeons was always present in the
preparations which render the purified food mixture
capable of promoting growth. They finally adopted
an alcoholic extract of wheat germ as a source of
this dietary factor in their investigations. Funk
an(J his co-workers had previously shown that the
curative substance is present in many natural
foods. ^* Repeated trials showed that the inclusion
of the alcoholic extract of wheat germ or of other
food, was not sufficient to induce growth unless
the butter fat was likewise added to the purified food
mixture. Both the growth-promoting fat and the
trace of unidentified substance in the alcoholic extract
of wheat germ are necessary for the promotion of
growth or the preservation of health.

It has been pointed out that Funk, in his examina-
tion of the various natural foods for the purpose of

30 THE NEWER KNOWLEDGE OF NUTRITION

determining the distribution of the antineuritic sub-
stance (substance which relieves polyneuritis) found
butter fat ineffective. This was later conjfirmed by
McCollum and Kennedy. ^^

Through the ''vitamine" hypothesis, Funk at-
tempted to account for the diseases beri-beri, scurvy,
pellagra and rickets, as being each due to the lack
of a specific chemical substance, a '^vitanaine," in
the diet.^^ This was a very lo^cal coQclusion from
the data available to Frnik. Scurvy, it had long
been known is relieved in a very spectacular manner
by the inclusion of fresh vegetables or orange juice
in the diet, and there was no doubt that the disease
developed as the result of a diet of poor quality. On
first consideration it seemed very reasonable to
assimie that there is an ''antiscorbutic vitamine''
in certain fruits and vegetables.

Pellagra has long been suspected of being due to
faulty diet, although the exact manner in which^he
diet is unsatisfactoiy renaained obscure. It "was
generally appreciated by clinicians that a change to
a highly nutritious diet in which milk and eggs were
conspicuous was the best prophylactic measure for
the treatment of the disease, and that without diet-
ary measures, all remedies fail. It was not surpris-
ing that Funk should have regarded pellagra as one
of the ''deficiency'' diseases, due to lack of a "vita-
jnine" in the diet. As will be shown later (Chapter V)
\ there has since been secuisd much experimental evi-
' dence in support of the view that scurvy and pellagra

BIOLOGICAL ANALYSIS OF FOOD-STUFF 31

do not arise from deJBciency in the diet of specific,
chemical substances in the sense in which Funkji
suggested. This seems to be true also of rickets.
In view of the considerations just mentioned rel-
ative to the cause of scurvy and pellagra, and the
convincing evidence that beri-beri is actually caused
by specific starvation for a substance, '*vitamine,''
as Funk suggested, McCollum and Davis formulated
in the following way, their working hypothesis as to
what constitutes an adequate diet. The diet must
contain, in addition to the long recognized dietary
factors, viz: protein, a source of energy in the form
of proteins, carbohydrates and fats; a suitable supply
of certain inorganic salts, two as yet unidentified
substances or groups of substances. ^^ One of these
is associated with certain fats, and is especially
abundant in butter fat, egg yolk fats and the fats
of the glandular organs such as the Uver and kidney,
but is not foimd in any fats or oils of vegetable origin.
The second substance or group of substances of
chemically imidentified native, is never associated
with fats or oils of either animal or vegetable origin.
It is widely distributed in natm^al foods, and can be
isolated in a concentrated, but not in a pure form,
from natural food-stuffs by extraction of the latter
with either water or alcohol. This water or alcohoUc
extract always contains the substance which cures
j>olyneuritis. At the time it seemed possible that
it also contained several other "vitamines,'' pro-
tective against the othei^diseases mentioned. The

32 THE NEWER KNOWLEDGE OF NUTRITION

fonner substance or group of substances, which is
associated with certain fats is not "curative" for
any of the list of diseases which Funk designated as
''vitamine" deficiency diseases. Indeed, butter fat,
which is the food containing one of the indispensable
substances in greatest abundance, was stated by-
Funk to contain no "vitamine.r ^^

Nomenclature of the Unidentified Dietary Essen-
tials . — ^The ending amine has a definite and specific
meaning in organic chemistry, and appUes only to
substances containmg the element nitrogen. Since
butter fat, which is very rich in one of the dietary
essentials in question is practically, if not entirely,
free from nitrogen, it seems almost certain that the
physiologically indispensable substance which it con-
tains is free from nitrogen, and could not with pro-
priety be designated by any name ending in amine.
For this reason, and because it is possible to divide
the unidentified constituents of the normal diet into
two classes on the basis of their solubiUty, McCollum
and Kennedy ^* proposed the terms fat-soluble A
and water-soluble B to designate them. The former
prevents the development of a pathological condition
of the eyes,^® the latter prevents the development of
^ beri-beri. As wiU be shown later, there is much
\ evidence for and none against the view tl\at what we
\designate by each of these terms is in reality but a
teingle physiologically indispensable substance and
kiot a group of substances. This necessitates the
ifurther assimiption that certain of the diseases 6f

BIOLOGICAL ANALYSIS OF FOOD-STUFF 33

dietary origin, which Funk held to be due to "vi-
tanaine" starvation, are in reality due to other causes.
This view will be supported by further evidence later.
Indeed it is not possible to longer regard scurvy as
a "vitamine" deficiency disease.

The '' vitamine'' hypothesis of Funk was extremely
attractive and seemed to account for the etiology
of several diseases in a most satisfactory way. It
seemed to rest upon sound observations, but in
reality it rested only upon suggestive chemical ev-
idence. It failed to stand the test of a systematic
investigation of all the more important natiu-al
food'StuSsy by the biological method which was
described in its essential features in illustrating the
nsbture of the dietary deficiencies of the wheat kernel.

CHAPTER II

EXPERIMENTAL SCURVY AND THE DIETARY PROPERTIES

OF VEGETABLES

McColluin, Simmonds and Pitz * sought to t^
the vaUdity of the "vitaniine" hypothesis in its
relation to scurvy, by an indirect method. The next
logical step in the investigation of the possible num-
ber of dietary essentials of unknown chemical nature
which occur in the growth-promoting fats (fat-
soluble A), and in the preparations which are never
associated with fats (water-soluble B), seemed to be
to study the oat kernel. There seemed much reason
to believe that this seed would prove to be unique
among the ordinary seeds in its dietary properties.
Theobald Smith ^ had, in 1895, called attention to the
fact that a diet of oats would cause in guinea pigs
the development of a condition suggestive of scurvy.
In 1909 Hoist and his co-workers in Sweden ^ de-
scribed munerous experiments involving the produc-
tion and relief of experimental scurvy in the guinea
pig. Hoist observed that when this ammal is re-
stricted to a diet of oats it rarely fails to develop
scurvy within a few weeks. The disease which is so
produced is strikingly suggestive of scurvy in man.
There is pronounced swelling of the knee and elbow
joints, with rupture of the capillaries at these sites,

DIETARY PROPERTIES OF VEGETABLES 35

and there is also a spongy and hemorrhagic condition
of the gums.

Hoist stated that the disease was due to a deficiency
of the oat kernel in an antiscorbutic substance, which
is relg^tively imstable when manipulated in the lab-
oratory. Milk was sta ted to be efficient Jor the_ cure
of the disease induced by an oat diet, prodded it was
raw or had not been heated to very high tempera-
tures. Milk which had been heated to 90° C. for
ten minutes was said to be still effective, but boiled
milk failed to induce a cure. Raw cabbage was
stated to be highly efficient as a remedy against
the disease m the gumea pig, whereas cooked or
dried cabbage had lost most of its antiscorbutic
property.

In view of these observations, it seemed that, if
it were true that scurvy is as Funk and Hoist be-
lieved, a disease resulting from ^^vitamine'' defi-
ciency^, the oat kernel should prove to be a natural
food-stuff which lacked the antiscorbutic '' vitamine"
but contained the anti-beri-beii, and perhaps, also,
the anti-pellagra and other '' vitamines. '' McCollum,
Simmonds and Pitz^ submitted the oat kernel to the
systematic procedure of the biological method of
analysis, feeding it as the sole source of nutriment,
and also with single and multiple additions of purified
food substances, employing the rat as the experi-
mental animal. (This showed that the oat kernel
(rolled oats) can be supplemented by the addition of
a salt mixture of appropriate composition, a growth-

36 THE NEWER KNOWLEDGE OF NUTRITION

promoting fat, and the purified protein gelatin, so as
to induce growth at the maximum rate in young rats
from weaning time to the full adult size, and sup-
ported the production of a few young. When any
one of these additions is onoitted, the animals fail to
develop. ^

The oat kernel, therefore, contains all the dietary
essentials in the water-soluble group (provided there
is more than one such substance). Like wheat it
lacks a sufficient amount of the fat-soluble A to
support normal nutrition. It was impossible to
harmonize the i;86Ults described by Hoist in the
production of experimental scurvy in the gumea pig
with those of McColliun, Simmonds and Pitz, in
which the rat served as the experimental animal,
without making assumptions which would greatly
compUcate the whole subject of nutrition investiga-
tions. There were serious discrepancies in the ex-
perimental data from different sources. Hoist's
studies pomted to the existence m the normal diet
of a substance or substances of unknown character,
which were easily destroyed by heat or by dessica-
tion, and which act as protective agents agamst
scurvy in the gumea pig, and appeared to demon-
strate that the supposed antiscorbutic substance or
substances were absent from the oat kernel. The
studies with the rat demonstrated beyond con-
troversy, that at least for the rat, (the oat kernel is
deficient as a food only as respects the factors, in-
organic salts, fat-soluble A, and in a lesser degree in

DIETARY PROPERTIES OF VEGETABLES 37

the quality of its protein. When these factors are
corrected, the oat kernel becomes a complete food
far this species.

\Scurvy has been produced experimentally by
faulty diet in the guinea pig, and is not known to
occur in any species other than man and the guinea
pig.y If the explanation of Hoist and of Funk is cor-
rect that scurvy is the( result of the lack of a specific
substance in the diet, it becomes necessary to make
the further assumption that man and the guinea pig
require this substance, since both suffer from the
disease, whereas other species, as the rat, do not re-
quire this complex as a dietary component.^ The
only alternative is to conclude that scurvy is in
realty not a "deficiency" disease in the sense in
which Funk and Hoist employed the term. That
there is actually no such unstable "antiscorbutic
substance'' or "antiscorbutic vitamine'' as postu-
lated by Hoist and Funk, has been demonstrated by
the studies of McCoUimi and Pitz.* The proof of
this is given in Chapter V. In the same chapter will
be discussed the other so-called "vitamine'' deficiency
diseases, pellagra and rickets, and the character of
the diets which play a part in their etiology. The
data available supports the view that among the list
of so-called "deficiency'' diseases, beii-beri, scurvy,
pellagra and rickets, only the first is due to the lack
of a specific protective substance. Funk's " vitamine,"
or water-soluble B in the diet. The others are at
least in some degree the result of faulty diets, but not

38 THE NEWER KNOWLEDGE OF NUTRITION

in the sense in which Funk and Hoist employed the
term ''deficiency/' McColliun and Simmonds have
pointed out, however, that in the pathological con-
dition of the eyes, known as xerophthalmia, of dietary-
origin mentioned above, we have a second deficiency
disease, analogous to beri-beri.^ All the facts at
present available point, therefore, to the belief that
what McCollum and his co-workers term water-
soluble B, is in reality but a single physiologically
indispensable substance.^ There is no evidence in
support of the view that th^ term fat-soluble A need
be considered as applying to more than a single
chemical substance. Xeropthalmia of dietary origin
will be described later (Chapter V).
^ Similarity of the Seeds from the Dietary Standpoint.
— ^By the application of the biological method
of analysis of a food-stuff to each of the more im-
portant seeds employed in the nutrition of man and
animals, the fact was brought to light that they all
resemble each other very closely in their dietary
properties. The fist of seeds examined included, —
wheat,^ com,^ rice,^^ rolled oats, rye,^ barley,^ kaffir
corn,^ millet seed,^® flaxseed,^® pea^® and both the
navy" and the soy bean.^( These all contain proteins
which are of distinctly lower biological value for
growth than are the proteins of milk ; they all are too
poor in the same three inorganic elements, calcium,
sodium and chlorine. All are, with the exception of
millet seed, below the optimum in their content of
the dietary factor, fat-soluble A. These three diet-

s -a 1 2, 1 s s

•s § § I • ^;

if 111'

^life-Ill

DIETARY PROPERTIES OF VEGETABLES 39.

ary factors must be improved before any one of these
seeds becomes complete from the dietary stand-
point. The seeds are, therefore, to be classed to-
gether as regards their food values. J

Since the seeds have the same faults from the diet-
ary standpoint, it is to be expected that when fed ih
mixtures they should not supplement each other ex-
cept as regards the protein moiety. It would hardly
be expected that the proteins of two or more kinds
of seeds should be deficient in the same amino-acids,
and in the same degree, and feeding trials have shown
that naixtures of seeds furnish better protein values
for growth than do the single seeds when fed alone,
properly supplemented with respect to all other
factors. (From the similarity of the inorganic con-
tent of all seeds, and their low content of the fat-'^
soluble A, it should be necessary to supplement any
mixture of seeds with respect to both these factors
before good nutrition can be secured. Experimental
trial shows this to be the case. It is not, therefore,
possible to secure appreciable growth in young animals
fed exclusively upon seed products as the sole source of
nutriment,^)

Casual observation teaches us that such animals
as the ox, horse, sheep and goat can grow and Uve
for years in a vigorous condition on diets derived
entirely from vegetable sources. After having un-
successfully attempted numerous times to induce
growth in animals fed strictly upon seed mixtures,
the thought naturally arose that there must be some

40 THE NEWER KNOWLEDGE OF NUTRITION

special properties in the leaves of the plant which
cause them to make good the dietary deficiencies of
the seeds. A careful inquiry in every possible direc-
tion failed to discover any animal which in its natu-
ral state limits its diet strictly to seeds. Birds all
appear to vary their diet of seeds with insects and
worms, and most birds eat to some extent of fruits
and certain tender leaves. All birds probably eat a
considerable amount of mineral substance in the
form of particles which they deliberately swallo\v;,
and they secure in their ^jiitural state more or less of
all of the essential inineral elements in the drinking
water which has permeated the groimd. These sup-
plemental sources of certain food substances, jp^hich
one is at first inclined to oVerlook, or if considered,
to regard as of an accessory nature, and therefore,
if ''accessory," -dispensable, are in reaUty of/SUch
importance, that it is not too much to say that the
preservation of the species might turn upon the
opportunity or lack of opportunity, to secure these
substances.

Among the onmivora, the author has been unable
to discover any species which subsists entirely upon
seeds. The hog is a typical omniverous feeder, but
it is well known to animal husbandrymen that there
are but two successful methods of pork production,
one of which is to feed growing pigs on grain while
they have access to a good pasture; the other is to
feed them milk, skim milk, or butter-milk, along
with a grain mixture. Ignorance of this factJias re-

ill!
lil|f

*J . S|

lip!

□ "^ S § "-3

"Jill

DIETARY PROPERTIES OF VEGETABLES 41

suited in enormous economic loss to farmers who
have attempted to keep growing pigs in a dry lot
and feed them cereal grains and by-products derived
from these, as the sole source of nutriment. Little
growth can be secured under these circtunstances,
and the reason becomes clear from what has been
said above concerning the nature of the dietary
deficiencies of the seeds and the similarity of the
^ seeds from the dietary standpoint.*

It was a great surprise to McCollum, Simmonds
and Pitz ^^ to find that appropriate mixtures of leaf
and seed make fairly satisfactory food mixtures for
the support of growti&i, whereas, as has been stated,
they were unable to secure any appreciable growth
in animals fed exclusively on seeds and seed products,
the drmkmg water suppHed being distilled and there-
fore salt free. The first leaf which was studied was
that of the alfalfa plant, for the reason that the
ground, immature aKalfa plant is extensively mar-
keted as a supplementary feed for pigs, and through
the courtesy of the Peters Milling Company of
Onaaha, Nebraska a product ''alfalfa flour'' was
made available in a convenient form. This consists

* It is not to be understood from this that it is intended to imply
that no increase in body weight can be secured in hogs when they are
confined strictly to grain mixtures. They may indeed become very
fat, and therefore' apparently grow for a time on such foods as com
alone. Even under farm conditions, where they are able to secure
a supplementary mineral supply through the water they drink and
through the consumption of soil with the grain, there is Uttle growth
in the sense that the muscle and organ tissues increase in volume.

42 THE NEWER KNOWLEDGE OF NUTRITION

of the dry, immature leaf of the plant ground to a
very fine powder of a bright green color.

A series of diets consisting of seed, 60 per cent,
and of alfalfa leaf flour, 40 per cent, were first
fed to growing rats. The seeds employed, included
wheat, com, rolled oat, rye, millet seed, kaflfir com,
pea and bean. The .degree of success in inducing
growth with most of these simple naixtures of one
seed with the alfalfa leaf is much greater than can ever
be secured with even such complex mixtures of seeds
as com, wheat, oat, hemp seed and naillet seed in
equal proportions. The latter mixture can support
a fair amount of growth when its inorganic defi-
ciencies are made good, but without mineral addi-
tions almost no growth can be secured. Chart 6
shows typical growth curves which give an accurate
idea of the relative values for growth of several
combinations of the alfalfa leaf with seeds. Among
the seeds with which studies have been made, the
oat is best supplemented by the alfalfa leaf. A
simple mixtm^ of rolled oats, 60 per cent, and alfalfa
leaf, 40 per cent, induces nearly nomaal growth to
the adult size in the rat and induces a fair amoimt
of reproduction and rearing of young. However,
the animals fall considerably below the maximum
performance in both these respects.

An examination of other leaves of plants showed
that the latter can in a general way be classed to-
gether as food-stuJBfs of similar character, since they
resemble each other more or less closely, just as the

•4|l|lliJ|
illjlls^l

l|'l|Pl|

;IIJ

DIETARY PROPERTIES OF VEGETABLES 43

seeds all resemble each other in their dietary prop-
erties. The leaf proves to be a very diflferent thing
from the seed from the dietary standpoint. The diy
leaf usually contains from three to five times as
much total ash constituents as does the seed, and
is always especially rich in just those elements in
which the seed is poorest, viz., calcium, sodium and
chlorine. It follows, therefore, that the leaf supple-
ments the inorganic deficiencies of the seed. The
leaf, in most cases, contains much more of the dietary
essential, fat-soluble A, than is found in any seed,
so that combinations of leaf and seed prove more
satisfactory for the nutrition of an animal than do
mixtures of seeds alone. The leaf contains protein
and amino-acids which result from digestion of pro-
teins as does the seed. The amoimt varies from 8
per cent of protein (nitrogen X 6.25) in such fleshy
leaves as the cabbage, after drying, to more than
15 per cent in the diy alfalfa or clover leaf. The
seeds vary in their content of protein from about 10
to 25 per cent. The leaf proteins appear, from
the data available, to supplement and enhance in
some degree the value of the seed proteins with which
they are combined. The leaf supplements, therefore,
all the nutritive deficiencies of the seed, but not
necessarily m a highly satisfactory manner.

It is mterestmg to reflect upon the reasons why
the leaf of the plant should show such decided dif-
ferences in its nutritive properties as contrasted
with the seed. A consideration of the difference in

44 THE NEWER KNOWLEDGE OF NUTRITION

function of the two gives the clue to the cause. The
seed consists of a germ, which forms in most cases
but a very small part of the entire seed, together
with a relatively large endosperm. The germ con-
sists of Uving cells, which respire and are capable of
multiplication (germination) when the conditions
are favorable. In the wheat kernel the germ con-
stitutes about 5 per cent of the entire seed. The
endosperm, on the other hand, consists largely of
reserve food materials such as protein, starch,
sugars, fats and mineral salts. It is not Uving matter,
and contains few cellular elements. The endosperm
is, therefore, in most respects comparable to a mix-
ture of purified food-stuffs. There is, as experiments
have abundantly demonstrated, relatively little of
the dietary factor, water-soluble B, in the endosperm,
and relatively much in the germ or embryo. The
same is true for the second unidentified dietary
factor fat-soluble A. This is practically absent from
the endosperm, but is fairly abimdant in the germ.
Since the latter represents so small a portion of the
entire seed, the seed itself is too poor in this sub-
stance, in nearly all cases, to supply the needs of a
growing animal.

The leaf of the plant, on the other hand, is very
rich in cells, and in most cases contains but little re-
serve food material. It is the laboratory of the plant.
Chlorophyll, its green pigment, enables it to make
use of the energy of the simhght, and from the
carbonic acid gas which it absorbs from the air,

S » i f I

"11 1"

|a|| a
•9 ^ S- g «

9 J;

! E B'sS

5 8 g

i Bi-s

qil

DIETARY PROPERTIES OF VEGETABLES 45

together with water and mineral salts, which it
absorbs from the soil through its roots, it builds
up proteins, starch, sugars and fats, which are used
for the growth of new plant tissue, or for storage in
the seed, tuber or other storage organs. The sur-
faces of the leaf are a mosaic of living cells. They
contain all the chemical complexes which are nec-
essary for the nutrition of the animal cells, and are
qualitatively complete foods.

The quality of the leaf from the dietary standpoint
may vary to a considerable extent. Some leaves are
thin cellular structures, which dry easily in the sun
when separated from the plant. In others, as the
cabbage, the leaf is in some degree modified as a
storage oi^an, and contains a considerable amount
of sugars. The cabbage leaf likewise contains more
than the ordinaiy amount of cellulose, which is its
skeletal tissue. Its dietary properties are modijfied
by these peculiarities in that the cellular elements
are diluted by the more inert tissues and reserve
food substances in the leaf. The freer a leaf is from
the function of a storage tissue, the more intensified
will be its leaf properties as a food. The fleshy leaves
tend to have in some degree the dietary properties
of the seed, and stand intermediate between the
leaves, which are thin, and dry easily, and the seed
in this respect.
^ The Tubers. — ^After the seeds, the tubers of cer-
tain plants constitute one of the most important
classes of energy-yielding foods. The potato and

46 THE NEWER KNOWLEDGE OF NUTRITION

sweet potato are by far the most important rep-
resentatives of this group in Europe and the Amer-
icas, but several other kinds of tubers are widely
used as human food in the Orient. An examination
of the potato has been recently made, which reveals
the special dietary properties of this tuber to be just
what we should expect from its fimction as a storage
organ for reserve food in the plant. The fimctions
of the potato are twofold, viz., to reproduce the
plant in the following generation, and to furnish
a food supply for the young potato plantlet while
it is developing root and leaf systems which make
it independent of the food stored in the old tuber.
The ''eyes" of the potato represent groups of cells
which are analogous to the germ of the seed. These
are the points at which the potato sprouts when the
conditions are appropriate. There is underneath
the skin of the potato a layer of cells which are alive
'and respiring during the life of the tuber, but the
interior of the potato consists almost entirely of
water, starch, protein, and to some extent of mineral
salts. The cellular structures in the interior are
gorged with starch, etc., and this portion is therefore
analogous in its dietary properties with the endo-
sperm of the seed. Both-^are comparable to a mixture
of purified protein, carbohydrate, and salts, which,
as we have previously seen, is not capable of support-
ing life. This portion, like the portion of the rice
kernel, which remains after poUshing, is almost
lacking in both the chemically unidentified dietary

DIETARY PROPERTIES OF VEGETABLES 47

essentials, fat-soluble A and water-soluble B, and
accordingly cannot support life even though it may
have an appropriate chemical composition as shown
by analysis. The potato is to be classed with the
seeds in its dietary properties, because it consists
largely of reserve food materials and relatively Uttle
of cellular elements. The results available indicate
that if the potato is steamed and the thin paperlike
skin removed without the loss of the cellular layer
which lies just imdemeath, it will contain relatively
more of the fat-soluble A, a lack of which leads to
the development of the peculiar eye conditions pre-
viously described, than do the cereal grains. Al-
though it has not been subjected to experimental
test, it would seem that a potato which is pared in
the ordmary way and the paring discarded, is
changed in its dietary properties in much the same
way as is the rice kernel during the poUshing process.
In the latter, the germ and the bran layer are both
rubbed off, leaving the endosperm without the small
quota of cellular elements which it possessed in its
natural state, and is correspondingly changed in its
food value (see legend to Chart 3). The protein of
the potato is not quite so valuable for growth as that
of the cereal grains when fed as the sole source of
this dietary factor.^

There have been a number of experiments of short
duration which gave results which indicate that in
the human subject the nitrogen of the potato is of
extraordinary value for replacing that lost through

48 THE NEWER KNOWLEDGE OF NUTRITION

daily metabolism in the adult. McCollum, Sim-
monds and Parsons, have tested this question by
comparing with the protein of the cereal grains the
value of the nitrogen of the potato when this tuber
was supplemented in such a manner as to make
good all of its dejficiencies except protein. The
experiments involved growth tests in the yoimg rat.
The results show conclusively that potato nitrogen
falls considerably below the value for growth pos-
sessed by the individual cereal grains, when each of.
these serves as the sole supply of the digestion prod-
ucts of protein.

The Roots Employed as Food. — The same rea-
soning appUes to the root crops as to the potato,
with respect to the relation between dietary prop-
erties and biological function. The roots which we
employ as food are those which are highly modified
as storage organs, and resemble the potato in con-
taining a very high water and starch content, and
but very little protein. Like the potato, there is a cel-
lular layer at the periphery, and the interior is loaded
with reserve food-stuffs. Appropriate feeding tests
have shown that the properties of the beet resemble
those of the seed and the tuber, rather than those of
the leaf.^ The fleshy roots and the potato and the
sweet potato have an inorganic content which re-
sembles that of the seed in a general way, so that an
inspection of the analytical data relating to the
composition of the ash of the seeds, tubers and roots,
gave no promise that the combination in diets of

DIETARY PROPERTIES OF VEGETABLES 49

seeds with either of the latter classes of food-stuffs
would correct the inorganic dejficiencies of the former.
Feeding experiments in which a seed and a tuber
were combined, and so supplemented with purified
protein, and fat-soluble A (in butter-fat), that all
the deficiencies of the mixture, except the inorganic,
were mtade good, have shown that in the combinations
of each of the more important seeds with the potato,
the resulting mineral supply, which is derived solely
from the natural foods themselves, is not of a char-
acter suitable for the support of growth.^ The con-
tent of the elements, calcium, sodium and chlorine
must be augumented by greater amoimts before such
food mixtures are complete \^dth respect to their
mineral content. No studies have as yet been made
to determine the biological value of the nitrogen of
the tubers other than the potato, and none at all of
the edible roots.

/FToxn. the results of systematic feeding trials with
"mixtures of seeds alone and the same with single and
multiple purified food additions, and the same type
of experiment using certain of the tubers and root
foods in place of the seeds, it is shown that all these
classes of foodstuffs resemble one another in all re-
spects except in the high content of water in the
tubers and roots. In the dry state they are all much
like the seeds, but there is one minor difference which
should be mentioned. The most important difference
lies in the character of the nitrogenous compounds.
In the seeds the nitrogen is almost all contained in

50 THE NEWER KNOWLEDGE OF NUTRITION

the form of true protein. In the tubers and edible
roots most of it is in the form of much simpler cona-
poimds, a part being the same amino-acids which are
derived from proteins on digestion.

It is possible to prepare diets derived solely from
vegetable products which will nourish an animal
during growth and throughout life in a very satis-
factory manner, but it is a surprisingly difficult task
to prepare for the omnivera, an adequate diet com-
posed entirely of food-stuffs of plant origin. While
many of the seeds contain nothing of a detrimental
character, many of the leaves, when e^ten, undoubt-
edly do introduce iMo the body substances which
have more or less mjurious effects. The nature of
these cannot be stated at the present time, but the
possibility that there noay be an injurious effect
brought about by prolonged admhxistration of such
bodies as the tannins, the glucosides and oxalic acid,
certain organic bases which in some cases resemble
certain of the alkaloids, and in some leaves the pres-
ence of alkaloids which are highly active pharmaco-
logically, can easily account for the fact that with
all rations of strictly vegetable origra one would
not have optimum nutrition. McCoUum and Sim-
monds have in a long list of trials with rmxtures of
leaves and seeds been imable to secure the opti-
mum of well-being in omnivorous animals. It is
worthy of the greatest emphasis that in our hundreds of
trials with diets derived entirely from vegetable sources,
we have not succeeded in yroducing optimum results in

DIETARY PROPERTIES OF VEGETABLES 51

the nvirition of an omnivorous animal the rat Certain
of the animals which we have restricted to foods of
plant origin, have done so well that we should in the
absence of much experience with diets of excellent
quality, have considered them to be normal in every
respect. It should be emphasized that the average
performance of a group of people or animals living
upon a varied diet cannot safely be assumed to repre-
sent the best of which they are capable. In the
study of diets the author and his colleagues have
kept constantly in mind the best results we have ever
seen in the nutrition of animals, as exemplified in
rapidity of growth, ultimate size attained, number of
young produced, and the success with which these
were reared, and have attempted to assign to every
experimental group its legitimate place on a scale of
performance, which has complete failure to either
grow or long remain alive as the one extreme, and
the optimum of which the animal is capable as the
other.

In connection with the statement which has just
been made regarding the strict vegetarian diet, that
it does not, so fa r^as has bee n observed, induce the
best r gsultsin the nutrition ofthe omnivorai it should^
be addea that inTTiuman dietary practice what"is
generally designated as vegetarianism is in reaUty
something very different. Many people hold that
they are adhering to vegetarian dietary habits, who
in reality, take in addition to foods of plant origin,
milk or eggs or both.. This type of diet will give very

52 THE NEWER KNOWLEDGE OF NUTRITION

much better results than can be secured from the
use of vegetable foods alone. Lacto-vegetarianism
should not be confuesd with strict vegetarianism.
The former is, when the diet is properly planned,
the most highly satisfactory plan which can be
adopted in the nutrition of man. The latter, if
strictly adhered to, is fraught with grave danger _
unless the diet is planned Jbj^one who has extensive
and exactJmoWledge of the speciahproperties of the .
various food-stuffs employed.

CHAPTER III

THE VEGETARIAN DIET

It has been pointed out in the preceding chapters
that it is not possible to make a diet derived entirely
from seeds or seed products, which will adequately
nourish an animal during growth, and it may be
added that such diets will not even maintain a fully
grown animal in a state of health and normal physi-
ological activity over a long period. Without an
appropriate supplementing of seed mixtures with
the 9lements, calcium, sodium and chlorine, no ap-
preciable amount of growth has been seemed with
seed mixtures, in our extensive experience. It was
further pointed out that the leaf is a very different
thing from the seed, tuber or root, from the dietary
standpoint, and these differences in nutritive prop-
erties can be correlated with differences in function.
The seed is a storage organ of the plant, and is jfiUed
with a reserve supply of proteins, carbohydrates,, fats -
and mineral salts. It is in great measure non-living,
matter, and indeed much of the contents of the^seed
was never a part of living matter, but only the prod-
uct of it. In the leaf of the plant we have a tissue
which, during life, was very active in the manifesta-
tions of the properties of living matter. With these

54 THE NEWER KNOWLEDGE OF NUTRITION

dififerences in function, it was pointed out, there are
found corresponding differences in the dietary values^
of the two types of foods, the latter being much more
nearly complete foods chemically, than are the seeds,^
tubers and roots. ^ ^ ^

Let us consider briefly the bearing of these obser-
vations on the whole subject of himian and animal
nutrition. It has been pointed out that for many
years the p rotein and energy value and its dig est-
ibility wftm f^rfisnnipd fri dH^rminp fh^ vainf* of a
fooi The chemist is able to determine approxi-
mately the amount of protein or rather its content
of nitrogen which is taken as a measure of the amount
of protein and the fuel value of a food, and by means
of experiments on animals, the extent to which a
given food is digested and absorbed. He can even
tell by a study of the relation between the amounts
of oxygen absorbed by the tissues, and the amount
of carbon dioxide given off whether the animal is
burning sugar or fat in order to obtain its energy.
The nitrogen eliminated in the urine serves as a meas-
ure of the destruction of protein in the body. With-
out in the least attempting disparagement of the
value of the services of the chemist in the study of
the problems of nutrition, it may truthfully be
said that both his ordinary and his unusual and
most searching methods for the analysis of food-
stuffs fail to throw any great amount of light on
the value of a food or mixture of foods for induc-
ing growth.

THE VEGETARIAN DIET 55

Id addition to the cereal grains, wheat, oat, maize,
rye, barley and rice, the products of the vegetable
garden . which supplied leafy vegetables, cabbage,
lettuce, spinach, cauliflower, brussels sprouts, chard,
celery, various ''greens," etc.; roots, such as the
radish, turnip and beet; tubers, such as the potato
and sweet potato, we have had available as food an
abundance of meats and of dairy products. It is
not strange that with such a supply of foods it should
have been taken for granted that any diet consisting
of wholesome foods, combined in such proportions
and taken in such quantities as would furnish
the amounts of protein and energy which exper-
iments on man and animals had shown to be neces-
sary imder specified conditions of living, whether at
rest or at work, should prove satisfactory for the
maintenance of health in the adult and of normal
growth in the young. An appreciation of the funda-
mental importance of employing proper combmations
of foods, was impossible, until the systematic efforts
described in the first two chapters, were made to
simplify the diet as far as possible, and to derive it
from restricted sources. These studies have, when
the results were applied to the interpretation of the
quality of the diets of man in several parts of the
world, revealed the fact that man is frequently
failing to make the wisest selection of food. Health
and eflBciency can be greatly improved by applying
the knowledge which we now possess concerning
the special properties of several classes of foods, to

56 THE NEWER KNOWLEDGE OF NUTRITION

the selection of the articles which shall make up the
daily diet.

The biological method for the analysis of single
food-stuflfs and mixtures of food-stuflfs has made it
evident that the older practice of regarding protein,^
energy and digestibility as the criteria of the valine of
a food mixture, must be replaced by a new method of
presentation of the subject based upon a biological
classification of the foodstuffs, the latter having its
foundation in the function of the substance employed
in the diet. Such a method of presentation of the
subject of food values offers convincing evidence of
the necessity, for the proper selection of food, that
dietary reforms are greatly needed in many parts of
the world.

There has been much discussion of the relative
merits of the vegetarian diet for man as compared
with diets largely derived from vegetable foods but
more or less Uberally supplemented with foods of
animal origin. This question has been discussed
principally from the point of view of the supposed
detrimental effects of a diet containing a high protein
content, and the supposed beneficial effects of a
sparing consimaption of protein, and from the point
of view that there are sound ethical reasons why
man should abstain from the use of animal foods.
The adherents of the latter extreme view have never
become nimierous, partly because the average in-
dividual has not the self-control to enable him to
forego the use of meats, milk and eggs, on account

THE VEGETARIAN DIET 67

of their appetizing qualities, and partly because the
chances of one's succeeding in the selection of a
strictly vegetarian diet which would maintain such
a state of physiological well-being as would make
possible the continuation of his line are very small.
Concerning the ethical considerations involved in
the eating of animal foods, nothing need be said here.
The relative merits of the vegetarian as compared
with the mixed diet, and the evidence regarding the
desirability of taking a low or high protein intake,
may next receive our attention.

The most elaborate attempt to test the relative
merits of the strictly vegetarian diet as contrasted
with the omnivorous type, was made by Slonaker.^
He fed a group of young rats on a list of 23 vegetable
foods, allowing them free choice within limits. For
comparison, a similar group were fed the same foods
of vegetable origin, but in addition animal food was
given in moderate quantities. Since several natural
foods, raw or prepared, were offered at a time, and
the animals were allowed free choice as to what they
should eat, and since no effort was made to keep
track of the food consumption, or the relative
amounts of the different foods eaten, the results
camiot be employed for critical examination except
m a liroited way. The results are of the greatest
interest in showing how far instinct fails to guide
an animal in the selection of its food. Slonaker's
list of foods included nearly everything which a
vegetarian' in southern California woifld be likely

58 THE NEWER KNOWLEDGE OF NUTRITION

to have on his table during the year, and included
seeds, the millmg products of seeds and leafy veg-
etables, tubers and roots.

The vegetarian group grew fairly well for a time,

but became stimted when they reached a weight of

about 60 per cent of the normal adult size. They

never increased in size beyond this point. The^

omnivorous controls grew steadily to what may be

regarded as the normal* size for the adult/ ^The

vegetarians lived, on an average for the entire group,

y555 days, whereas the omnivora had an average span

/oi life of 1020 days. The vegetarian rats grew to be

.--^proximately half as large, and lived half as long

as did their fellows which received giTiimal ff>ofl._

Slonaker drew the conclusion that a strictly veg-
etarian diet is not suitable for the nourishment of an
omnivorous animal, but was imable to say why this
should be true.

The results of Slonaker were published in 1912,
and just at the time when McCollum and Davis were
seciwing the experimental data which revealed the
differences in the growth-promoting power of fats
from different sources and which established the
fact that a hitherto unsuspected dietary essential
existed. They fed their diet of relatively pure food-
stuffs described' on page 16 with various fats of both
animal and vegetable origin and found that no fat
which was derived from plant tissues came in the
growth-promoting class along with butter fat, the
fats of egg yolk, and of the glandular organs. It

THE VEGETARIAN DIET 59

seemed to McCoUum and Davis that the most
probable explanation of the results of Slonaker was
the absence or shortage in his vegetarian diet of the
dietary essential which is furnished so abundantly
by butter fat, and which later came to be designated
as fat-soluble A and to a low protein intake. With
this idea in mind they tried dming the summer of
1914 an experiment similar to that of Slonaker's, but
modified so as to give the animals a much higher
protein content than his rats probably took. It
seemed that if Slonaker's vegetarian rats ate liberally
of such leaves as cabbage and other leafy vegetables,
the protein content of which in the fresh condition
does not as a rule exceed 2 per cent, the content of
other constituents of the diet in protein might not
be high enough to give the entire mixture consumed,
a protein content sufficiently high to promote growth
at the optimum rate.

McColliun and Davis, therefore, fed their rats a
diet which afforded them a choice ainong the follow-
ing list of foods : wheat, maize, rye and oat kernels,
cooked dry navy beans, peas, wheat germ, com
gluten, wheat gluten, flax-seed oil meal, green clover,
green alfalfa leaves, onions and peanuts. It will be
observed that in this list there are seveial vegetable
foods having unusually high protein contents. Com
gluten, which is a product of the com starch manufac-
ture, contains about 25 per cent of protein; wheat
gluten, prepared by washing ground wheat free from
starch, contains about 86 per cent ; flax-seed oil meal,

\^60 THE NEWER KNOWLEDGE OF NUTRITION

as much as 30 per cent; and wheat germ about 30 per
cent of protein. Since animals are known to grow
well on many diets containing 15 to 18 per cent
of protein, it seemed that with these things to
select from, one possible cause of failure in Slonaker's
experiments, viz., too low a protein intake, would be
avoided. McCollum and Davis had not at that time
discovered in the leaf the source of the dietary essen-
tial, fat-soluble A, although it. is now known that the
leafy foods enable the herbivorous animal to thrive
on his diet derived entirely from plant tissues. It was
then assumed that when both the leaves and so
many different seeds as well as the germ was supplied
there could be Uttle doubt that everything which a
herbivorous animal requires was present in the foods
suppUed.

The rats fed this wide variety of vegetable foods,
and with a most Uberal supply of protein, duplicated
in all respects the results which Slonaker had de-
scribed. They grew at about half the nornial rate
for the first few weeks, then became permanently
stunted, none ever reaching a size much greater than
haK that of the average normal adult. The addition
of butter fat to the diet of some of these animals
failed to benefit them in any noticeable degree. The
answer to the question as to why rats do not thrive
on such strictly vegetarian food mixtures was not
secured from these experiments. It was, however,
soon after learned wherein lay the cause of failure of
animals so fed.

THE VEGETARIAN DIET 61

, McC!ollitai, Simmonds and Pitz, began in 1915 a
series of feeding experiments in which the diets of
rats were derived solely from a mixture of one seed
and one dry leaf.^ In marked contrast to the failure
of animals to. grow on any mixtures of seeds it was
found that in many cases a mixture of a seed with a
leaf formed a diet on which considerable growth
could be secured. Even polished rice, which as has
been already described, requires four types of
supplementing, viz, protein, mineral salts, fat-
soluble A and water-soluble B, before it becomes
dietetically complete, was foimd to induce fairly
good growth when fed with groimd alfalfa leaves in
the proportion of 60 per cent of the former to 40 per
cent of the latter. On. this simple monotonous mix-
ture, young rats grew from weaning time to 83 per
cent of the normal adult ?'ze, and one female even
produced two litters of young, both of which were,
however, allowed to die vvithin a few days. A mix-
ture of rolled oats, 60 per cent, and alfalfa leaves,
40 per cent, ground together makes a very much
better diet. On this simple mixture yoimg rats have
been observed to grow to the normal adult size, and
to reproduce and rear yoimg. One female reared
fourteen out of seventeen young bom in three litters.
Maize and alfalfa leaf, wheat and alfalfa leaf, are
not so satisfactory for the production of growth as
is a mixture of rolled oats and alfalfa leaves. Mix-
tures of the latter leaf with legume seeds, peas and
beans, give still poorer results. (Chart 6.) These

62 THE NEWER KNOWLEDGE OF NUTRITION

results made it evident that there is nothing in
vegetarianism per se, which makes it impossible to
nourish an onmivorous animal in a satisfactory
manner. It is only necessary to make a proper selec-
tion of food-stuffs, and to combine them in the right
proportions. In all the experiments described, in
which the diet was made up of so simple a mixture
as one leaf and one seed, they had not obtained
the optimum of growth, reproduction or rearing of
young.

It seemed probable that the reason why they did
not more closely approximate the optimimi in the
nutrition of animals restricted to a cereal grain and
a leaf, might lie in too low a protein mixture, or a
protein mixture which was not of very high bio-
logical value. In 1915, McCoUum, Sioomonds and
Pitz ^ fed a group of young rats on a monotonous
DMxtm^ consisting of maize 50 per cent, alfalfa
leaf (dry) 30 per cent, and cooked (dried) peas, sub-
sequently dried, 20 per cent. The three ingredients
were ground together so finely that they could not
be picked out and eaten separately. This diet in-
duced growl h at approximately the normal rate and
the production and rearing of a considerable number
of young. The young grew up to the full adult size
and were successful in the rearing of their offspring.
Without ever tasting anything other than this mo-
notonous food mixture, as their sole source of nutri-
ment after the weaning period, this family of rats
renaained nearly normal, and successfully weaned the

THE VEGETARIAN DIET 63

young of the fourth generation, with no apparent
diminution in vitality. At this point the experiment
was discontinued.

The failure of Slonaker's rats to thrive on the
vegetarian diet is to be explained on the basis of
several faults. In the first place, the diet was of
such a nature that the animals could hardly do other-
wise than take a rather low protein intake. Sec-
ondly, the leaves, which formed the only constituents
of the food supply which, contained enough mineral
elements to support growth, were fed in the fresh
condition. In this form the water content and bulk
is so great that it would be practically impossible
for an animal whose digestive apparatus is no more
capacious than that of an omnivora, to eat a sufficient
amount of leaf to correct the inorganic deficiencies
of the rest of the mixture, which consisted of grains,
seeds, tubers, and root foods. The same physical
limitations would likewise determine that the a,nimal>s
would fail to secure enough of the fat-soluble A to
supplement the deficiency of all the ingredients of
their diet other than the leaves in respect to this
factor. This would not form so important a fault
as the inorganic deficiencies, but would be an im-
portant depressing factor. Thirdly, success or
failure would turn in great measure on the extent
to which the animals would be guided by instinct in
the selection of the proportions of the several types
of food-stuflfs which was offered them. In the opin-
ion of the author the appetite is by no means so

64 THE NEWER KNOWLEDGE OF NUTRITION

safe a guide for the proper selection of foods as has
generally been supposed.

From the results of the experiments just de-
scribed it was necessary to conclude that the leaf
differs from the seed in that it contains in satis-
factory amounts the dietary factors which are found
in the seeds in too small amoimts. These include the
% three inorganic elements, c alcium ^ s odium and chlo-
rme, the fat-solu ble A and a protein supply which
supplements atTeast in_some^degree the jgrgteins of
'theL_seed. These, it will be remembered, are the
three and only purified food factors which need be
added to each of the seeds singly in order to make it
dietetically complete. It is therefore, possible to de-
vise a diet which is derived entirely from vegetable
materials which will produce normal growth and
the optimum physiological well-being.

At the Iowa Experiment Station, Eward ^ has con-
ducted extensive experiments of a character which
were intended to demonstrate that the appetite and
instincts of the hog serve to enable it to make such
an adjustment of the relative amounts of the several
food-stuffs offered it, as may induce better results
in the rate of growth than can be generally secured
when the adjustment is made by the feeder, and
the mixture of the ingredients of the ration are offered
in a form which admitted of no choice by the animal.
The data secured in many trials seem to show that
there is some basis for the beUef that this element of
selection by the animal itself is worth taking ad-

THE VEGETARIAN DIET 65

vantage of. It should be mentioned that, as a rule,
in all these trials the animals were given a choice of
only three foods, one of these being a cereal grain,
another, a protein-rich food and a third a plant leaf.
In some experiments a salt mixture was made avail-
able. The reasons for the employment of the leaf
as a never faiUng constituent of the food supply of
the growing pig could not have been explained be-
fore the studies of McCoUum and his co-workers,
with simplified diets and with diets restricted as to
source to a single food-staff, and until the latter had
been fed with single and multiple food additions to
ascertain the exact nature of the dietary faults of
each. In connection with the types of diets em-
ployed by Eward it should be mentioned that in
case the animal ate fairly Uberally of all the food-
stuffs offered him, a serious mistake would be
hardly made, since the proportions of the several con-
stituents eaten could be varied to a considerable de-
gree and growth still take place. In the case of the
mixture of maize 50 per cent, alfalfa leaves 30 and
peas 20, described above (Chart 7) it has been found
that for the rat these are the best proportions in
which these three ingredients can be mixed for the
promotion of growth and reproduction. It has been
further established that using these three food-stuffs,
a moderate amoimt of growth may be secured, but
few, if any, young will ever be produced if the mix-
ture fed contains more than 50 per cent or less than
20 per cent of alfalfa leaf. The importance of com-

66 THE NEWER KNOWLEDGE OF NUTRITION

bining the natural foods in the right proportions is
easily seen from these results. It is interesting to
note further, that shifting the proportions of maize,
peas and leaf in this mixture over a range of 20 per
ctot does not materially change the protein content,
or indeed, the chemical composition of the food mix-
ture in any way, to a degree that could be expected to
make so great a difference in the state of nutrition
of the animals as is actually observed.

There are now available the results of a very ex-
tensive series of feeding trials in which the rations
were made up of one seed, one leaf and one legume
(pea, bean) in various proportions. These have
failed to reveal any mixture which is quite the equal
of the first ration of this type ever employed, viz.,
that composed of maize 50, alfalfa leaf 30 and peas 20
per cent. It is, of course, easily possible that better
mixtures of vegetable foods may be fotmd by further
search, but these results show very definitely that
for the omnivorous type of animal, whose digestive
tract is so constituted that the consumption of large
volumes of leafy foods is not possible, it is by no
means a simple matter, if indeed possible, to derive
the diet entirely from the vegetable foods, and se-
cure the optimmn of well-being. The data afforded
by the experiments described form a demonstration
of the fact that wide variety is of Uttle value as a
safeguard to nutrition. Chemical analysis, no matter
how thorough, fails to throw much Ught upon the
dietary value of a food-stuff. The only way in which

THE VEGETARIAN DIET 67

the problems of nutrition can be solved is through
numerous property planned feeding experiments,
but such studies were not possible before the solution
of the problem of successfully feeding mixtures of
purified food-stuffs. These studies led to the formula-
tion of an adequate working hypothesis regardiug
what factors operate to make an adequate diet, and
made possible the interpretation of the cause of
success or of failure with diets of the complexity em-
ployed in daily life. It will be sb nwn l^f-^r t.hat tht^.
con sumption of milk and its products forms the great -
est fac tor for the protection of mankind, in correcting
the faults in his otherwise vegetarian and meat diet.
The fact, that although the cereal grains each con-
tain every inorganic element which is contained in
an animal body, and every one which is a necessary
constituent of the diet, but in too small amounts
in the case of three of them, to enable the animals to
grow, revealed the mineral constituents of the diet
in a new and important light. The animal is sensi-
tive to either the actual amounts of certain of the
mineral elements in the food mixture, or to the re-
lationships among them. Sidney Ringer was led
in 1891 to his description of Ringer's solution, as the
result of the observations in physiology, that muscle
behaves more nearly normally in solutions con-
taining certain salts in definite proportions. Ringer's
solution contains, for each 100 molecules of sodimn
chloride, two molecules of calcium chloride and two
to one molecules of potassium chloride, together with

68 THE NEWER KNOWLEDGE OF NUTRITION

a trace of a magnesium salt. Loeb/ Howell ^ and
others had described many experiments showing the
profomid effects upon the subsequent development
of the eggs of varying in certain ways the composition
of the salt solutions in which unfertilized eggs of
certain marine animals were kept. In this way the
earliest stages of development which are ordinarily
observed only in the fertiUzed egg, could be caused
to take place in eggs into which no sperm had en-
tered. In the nutrition of the higher animals, it had
never been made clear how dependent the organism
is on the rate at which the blood stream receives
mineral nutrient. The fact that the cereal grains
are too low in three inorganic elements to admit of
growth, made it clear that food packages just as they
come from the hand of Nature, are not necessarily
so constituted as to promote health.

CHAPTER IV

THE FOODS OF ANIMAL ORIGIN

It is well known frona. common observation that
milk, when it serves as the sole food of the infant,
serves to keep it growing normally and in good
health over a long period. There has occasionally
arisen a discussion as to whether milk is a suitable
food for the adult, and as to whether it is the '4dear'
food. Milk, like the cereal grains and most other
natural foods, contains all the essential food elements,
and human experience teaches us that the proportions
in which they occur in this product are piuch more
satisfactory than in many other natural foods. An-
imals grow well on milk, but it is not easy to find
even complex food mixtures of vegetable foods which
will support optimum nutrition in the omnivora
during growth.

Milk is deficient in iron, as is shown by chemical
analysis. It has long been known that there is de-
posited in the spleen of the new-bom animal a reserve
supply of iron, which ordinarily suffices to tide it
over the suckling period. Ordinary drinking water
ahnost always contains small amoimts of iron, and
this doubtless aids in some degree in preventing iron
starvation in the infant.

70 THE NEWER KNOWLEDGE OF NUTRITION

That milk is a complete food, capable of supplying
all the nutrients necessary for the prolonged main-
tenance of growth, health and the ability to produce
and rear young, was shown by an experiment con-
ducted by the author at the Wisconsin Experiment
Station. A female pig was removed from its mother,
which was still nursing it at the weight of 17 pounds.
She had doubtless eaten of the mother's ration to
some extent but her prmciple food had been her
mother's milk. After removal from the mother,
this pig was confined in a pen having a board floor,
and was fed nothing but milk during a period of 17
months. During the first few months only whole
milk was fed, but later it was necessary to replace
this in part by skim milk. The animal weighed 406
pounds at the age of thirteen months. At this age
she produced eight living and two dead pigs, and
successfully brought the young to an average weight
of seventeen pounds. She had access to wood shav-
ings, and ate some of them. There can be no doubt
that the milk which she consumed was enriched to
some extent with iron by being in contact with cans
having part of the surface free from tin. City drink-
ing water was also furnished and this contained
appreciable amounts of iron. The animal must have
been able to conserve its limited iron supply in a
very efficient manner.

Milk is, therefore, capable of nourishing the pig
during many months, with no other modification
or additions than small amoimts of iron. That it is

THE FOODS OF ANIMAL ORIGIN 71

best to select milk as a monotonous and restricted
diet during adult life, no one familiar with the prin-
ciples of nutrition would maintain. Milk is, however,
without doubt our most important food-stuff. This
is true, because the c omposition of milk is such that
when use d in combination with ot her food stuffs of
either animal or ve getabk origin, it corrects their dietary
deficiencies. Combinations of equal weights of milk
and one of the cereal grains give excellent results
in the nutrition of animals during growth, and grain
mixtures supplemented with milk support well in
adult life the ftmction of reproduction and rearing
of yoimg. This is because of the excellent quality
of its proteins, the peculiar composition of its in-
organic content and the remarkable content of the
dietary essential, fat-soluble A, in the fats of milk.
Milk, like nearly all of the other natural foods, con-
tains a great abimdance of the second dietary essen-
tial of unknown chemical nature, water-soluble B.

The extraordinary value of the proteins of milk
has been abundantly demonstrated by experiment.
McCoIlmn ^ conducted a series of experiments with
growing pigs to determine the extent to which they
could retain the protein of the food for the construc-
tion of new body protein. The pig was selected be-
cause it is necessary in such studies to work with
an animal whose growth impulse is as great as pos-
sible. Only with such species is it to be expected
that the animal will utilize the proteins for growth
to the maximiun extent made possible by the chem-

' 72 THE NEWER KNOWLEDGE OF NUTRITION

ical character of the food protein. The human
infant has but little growth impulse because its
period of infancy is long and the adult size not great
as compared with the size at birth. A comparison
of the hiunan infant with the rat and the young pig
(swine) in their capacity to grow in early life is of
interest. The human infant weighs not far from
seven pounds at birth, and during the first year of
life is ordinarily able to multiply its initial body
weight by three, for the average weight at one year
is about twenty-one poimds. We may feed it hinnan
milk the entire time, or immodified cows' milk during
the greater part of tHe year, without in any important
degree modifying its rate of growth. In the latter
case, we should be supplying it with perhaps double
the amount of protein that it would receive were it
fed hmnan milk, since the latter contains on an aver-
age about 1.6 per cent and the former about 3.5 per
cent of protein.

In marked contrast to the feeble capacity of the
himian infant to store new tissue and increase in
size, stand the rat and the pig. The rat at birth
weighs about 4.83 grams, and contains about 0.064
grams of nitrogen. At 280 days of age the male
should weigh about 280 grams, and if moderately
fat will contaia about 8.5 grams of nitrogen. The
rat is able, therefore, in a period of 280 days to
multiply its initial body weight by about 55,
and its initial body nitrogen content (protein) by
133.

THE FOODS OF ANIMAL ORIGIN 73

The newborn pig weighing two pounds will con-
tain about 134 grams of dry matter and 11.9 grams
of nitrogen. In 280 days it may, if properly fed,
reach a weight of 300 pounds. It would then have
a nitrogen content of not less than 2407 grams.
These changes in size entail a multiplication of the
initial body weight by 150 and of the initial body
nitrogen content by 202. The farm pig is ap-
parently the most rapidly growing species of land
animals.

Such considerations determined the selection of the
pig as a subject for the test of the biological value
of the proteins of the various natural food-stuffs.
The plan involved keeping the animal for a period
of several days on a diet free from protein, but con-
taining sufficient starch to cover the energy require-
ments. When the nitrogen elimination in the urine
reached a constant low level which represented the
irreducible minimum, resulting from the ''wear and
tear" of the tissues, the animal was fed a diet con-
taining protein derived solely from a single grain,
or other single food-stuff. A record was kept of the
intake of the element nitrogen, and of the daily loss
of this element through the excreta, and from these
records the percentage retained for growth was ob-
tained. Similar experiments were carried out using
milk as the sole source of protein. The following
table simmiarizes the results obtained.

74 THE NEWER KNOWLEDGE OF NUTRITION

Per Cent op Ingested Protein Retained for Growth by

THE Pig

Per cent of ingested
Source of protein protein retained

Com 20.0

Wheat 23.0

Oats (roUed) 26.0

Milk 63.0

The figures in the table are averages of a consider-
able number of results and represent the general
trend of the data. The experimental periods varied
from 30 to 60 days. There can be no doubt that the
proteins of milk are far superior to those of any foods
derived from- vegetable sources.

The problem of determining the relative values of
the proteins of the different foods when fed singly , sup-
plemented with purified food additions that their diet-
ary deficiencies were made good, was approached in
a different way by McCoUum and Simmonds.^ Rats
were fed diets in which the protein was all furnished
by a single natural food-stuff, but the plane of protein
intake was varied from very low to higher intakes, in
Older to determine what was the lowest per cent^of
protein in the food mixture which would just suflSce
to maintain an animal without loss of body weight.
The rations consisted of the following substances :

Seed Amount to give the protein intake desired

Growth-promoting fat (butter-fat) 5.0 per cent

Suitably constituted salt mixtures . .3 to 5 per cent

Agar-agar (to fm-nish indigestible matter) 2.0 per cent

Dextrin To make 100 per cent.

THE FOODS OF ANIMAL ORIGIN 75

The results showed that there are indeed very great
differences in the amounts of protein from different
seeds, which are necessary to maintain an animal
without loss of body weight. The results for the
more important seeds used as human foods are
summarized in the following table.

Table Showing the Lowest Plane of Protein Intake De-
rived FROM A Single Seed Which Just Suffices to Main-
tain AN AinMAL IN Body Weight, when the Factors
Other than Protein are Properly Constituted

Source of Protein Plane of Protein Necessary for Maintenance

Milk 3.0 per cent of food mixture »

Oat (rolled) 4.5 "

Millet seed 4.5 "

Maize 6.0 "

Wheat 6.0 "

Polished rice 6.0 "

Flaxseed. 8.0 "

Navy bean 12.0 "

Pea 12.0 "

These maintenance experiments were of three to six months'
duration.

The data obtained with the pig is seen to be in
harmony m a general way with those obtained with
the rat, and help to substantiate the view which is
supported by all the evidence available, viz: that
from the chemical standpoint, the dietaiy require-
ments of one species of animal are the same as those
of another. That there are great differences in the
physical characters of the diet which suffice for,

tt i

((

tt t

((

tt i

tt 1

•t

tt I

76 THE NEWER KNOWLEDGE OF NUTRITION

or are required by certain species as contrasted with
others, is a matter of common observation. The
ruminants actually require coarse herbage as a part
of their food, in order that the alimentary tract may
fimction properly, whereas such physical properties
in the diet of the omnivora are wholly out of place
beyond very limited amounts.

In considering the value of milk as a constituent of
the diet it should be borne in mind that with respect
to the protein factor it may enhance the value of the
proteins of the remaiader of the food. It may supply
ia relative abimdance those amino-acids which are
present ia such small amoimts that they form the
first, second, etc., limiting factors in determining the
value of the protein for growth or maintenance, as
well as by the direct addition to the food naixture, of
the iatruisically good proteias of the nailk.

When taken as the sole food supply by the adult,
roilk is very liable to produce constipation and be^
cause of its high protein content, may lead to the ex-
cessive development of putrefactive bacteria in the
intestiae. The cages of rats fed solely on milk de-
velop an offensive odor. The addition of carbohy-
drate, such as starch or certaia of the sugars, tend
to cause the disappearance of the obnoxious flora from
the alimentary tract, and the development, instead,
of types which do not produce iajurious decomposi-
tion products ia their action on proteias.

Meats. — The muscle tissue of an animal ^con-
sists of highly spftfiialized tissue^hose ^dbief function

THE FOODS OF ANIMAL ORIGIN 77

is to produce mechanical work through contraction.
It is in addition a storage organ in which glycogen,
a form of starch, and also fats are stored as reserve
foods. It contains but httle of cellular structures in
the sense that the glandular organs, such as the
liver, kidney, pancreas, etc, do. Chemical analysis
shows the muscle to consist, aside from the reserve
food-stuffs, principally of water, protein and salts.
The glandular organs yield a high content of nucleic
acid, while the muscle tissue yields but little in pro-
portion to its weight. The inorganic content of the
muscle tissue resembles that of the seed of the plant,
rather than the leaf both in amount and in the rel-
ative proportions among the elements.

Corresponding with the speciaUzed function, and
the pecuUarities in composition just mentioned, we
find that its dietary properties are comparable
with the seed rather than the leaf. In fact; muscle
tissue differs markedly from the seed in only one
respect, when considered as a food-stuff, viz., in the
quality of its proteins. These are distinctly better
than those of the seeds with which investigations
have been conducted. The inorganic content must
be supplemented by the same inorganic additions as
the seed, and the musrfe proves to be relatively poor
in its content of the unidentified dietary essential
fat-soluble A, as compared with such foods as milk,
egg yolk and the leaves of plants.
V /"^"SSce the inorganic part of muscle resembles that
' of the seed, except that the latter is poorer in iron

78 THE NEWER KNOWLEDGE OF NUTRITION

and it is low in its content of fat-soluble A, it does
not supplement the seeds in an appreciable degree
other than with respect to the protein factor. It
follows, therefore, that we should not expect to se-
cure growth and normal nutrition with mixtures of
seeds, and meat and experimental trials demonstrate
that this is the case- Mixtures of meat (muscle)
and seeds requjre'To be supplemented with respect
to sodium, calcium and chlorine, just as do seed mix-
tures alone^. The fat-soluble A content of such
mixtures, unless millet seed is one of the seeds pres-
ent to the extent of 25 per cent, must be increased
by suitable additions before the optunum nutrition
can be attained, and the animals can successfully
bear the strain of reproduction and lactation. Meats
are, therefore, but partial supplementary foods when
employed with the seeds or the products prepared
from seeds, such as wheat flour, com meal, polished
rice, etc. Such diets can be partially corrected by
the liberal use of leafy vegetables, but better by the
use of the latter along with milk.

The pronounced deficiencies of muscle tissue as a
food-stuff ,• naturally suggests the question of the
reason for the success of the nutrition of the strietly
carnivorous animals. The explanation is foimd in
the order in which such creatures select the parts of
the carcasses of their prey. The larger camivorae,
after striking down an animal, immediately open the
large veins of the neck and suck blopd as long as it
flows. Their second choice of tissues is the liver, and

THE FOODS OF ANIMAL ORIGIN 79

following this the other glandular organs. Muscle
tissue is only eaten after these have been consumed.
With such a selection the animal secures eveiything
which it needs for its nutrition except a sufficient
amount of calcium, and this is obtained through
gnawing off the softer parts of the extremities of the
bones. The failure of many camivora to thrive when
confined in zoos, it probably the result of their being
fed too largely upon muscle tissue and bones. They
should be supplied with an abundance of the gland-
ular organs and with blood to make their diet com-
plete. With rats McCoUum, Simmonds and Parsons
have observed fairly satisfactory growth on equal
parts of muscle tissue (round steak) and dried
blood, whereas either of these alone cannot induce
growth.^

The Glandular Organs. — The liver and kidney
may serve as typical examples of the glandular or-
gans which are employed as foods. There are cer-
tain organs of mtemal secretion, such as the thy-
roid, and suprarenal glands which elaborate products
which are highly active pharmacological agents, and
the liberal use of these glands as food would lead to
disastrous consequences. The glands contain but lit-
tle of the inorganic elements in which the seeds are
deficient. Their proteins are probably of excellent
quality, but have not yet been carefully investigated.
The glands consist largely of actively functioning
cells, having specialized functions, and accordingly
they prove to contain a more liberal amount of both

80 THE NEWER KNOWLEDGE OF NUTRITION

the fat-soluble A and water-soluble B than does the
muscle. In respect to the former of the unidentified
dietary essentials the glandular organs surpass the
seeds in value. ^ From this description it will be
seen that the glandular organs approximate more
closely complete foods than does the muscle, but
it is likewise apparent that these tissues do not
form efficient supplements for the seeds and their
products.

Eggs. — The egg contains all the chemical com-
plexes necessary for the formation of the chick dur-
ing incubation. The egg is therefore to be expected
to furnish everything which is needed for the nutri-
tion of a mammal, for as has been already stated,
the evidence all supports the beUef that the chemical
requirements of one species are the same as another.
The egg is indeed a complete food, but not one which
produces the optimum results when employed as
the sole source of nutriment. Aside from the calcium
content of the white and yolk of the egg, which is
much lower than that of milk, the contents of the egg
resemble milk in a general way in nutritional value.
The high content of milk sugar in the latter, and the
almost complete absence of carbohydrate from the
egg, cause them to differ considerably in the physi-
ological results which they produce on animals when
each is fed as the sole source of nutriment. Egg,
when fed alone, encourages much more than milk
the development of putrefactive organisms in the
alimentary tract. The shell of the egg consists

THE FOODS OF ANIMAL ORIGIN 81

principally of calcium carbonate, and during in-
cubation this is to some extent dissolved and ab-
sorbed for the formation of the chick. When eggs
serve as human food the shells are discarded. There
are distinct differences in the chemical natures of
the constituents of eggs as contrasted with milk.
The principal protein of egg yolk, like that of milk,
contains phosphorus, but the fats of milk are phos-
phorus free, whereas phosphorized fats (e. g., leci-
thins) are very abundant in egg fats. There is an
abundance of lactose in milk, whereas the egg con-
tains but a trace of sugar. These differences have
little, if any, dietary significance. The yolk is es-
pecially rich in both the fat-soluble A and water-
soluble B. With the exception of milk the foods of
animal origin do not supplement completely the diet-
ary deficiencies of the seeds and their products.
^ We are now able to make certain generalizations
of fimdamental importance regarding the types of
combinations of the natural food-stuffs which may
be expected to give good results in the nutrition of
an animal.

(1) Seed mixtures, no matter how complex, or
from what seeds they are derived, will never induce
optimum nutrition.

Seeds with tubers, or seeds with tubers, roots and
meat (muscle) will in all cases fail to even approxi-
mate the optimum in the nutrition of an animal
durmg growth.

(2) The only successful combinations of natural

82 THE NEWER KNOWLEDGE OF NUTRITION

foods or milled products for the nutrition of an ani-
mal are:

(a) Combinations of seeds, or other milled
products, tubers and roots, either
singly or collectively taken with Ef-
ficient amounts of the leaves of plants.

(b) Combinations of the food-stuffs enu-
merated imder (a) taken along with a
sufficient amoimt of milk to make good
their deficiencies.

Milk nn 4 fh/i l/>^ i)p^^ of plc^nt arp. Iq hf, rpqardpA as

protectwejoods and s hould ^^*^^ h^ <mittf^ frnfn. the
diet^ Milk is qbetterprvte^^
when use d in approji rjof^' g^/yimfji.

It should be appreciated that not all diets which
conform to the requirements laid down in the above
generaUzations, will give equally good results. This
is especially true of diets of the type imder (2).
Chart 6 shows the great differences in the food
values of a few mixtures of seeds and leaves. It can
be stated definitely, however, that diets which are
not made up according to the second plan, will
never be satisfactory.

CHAPTER V

THE DISEASES REFERABLE TO FAULTY DIET, OR THE
SO-CALLED '^ DEFICIENCY DISEASES''

It h^ been pointed out that m the year 1911 Funk
took up the study of the disease beri-beri. He made
use of the observation of Eijkman, that the symp-
toms could b^ produced experimentally in birds by
feeding them exclusively upon polished rice for two
to four weeks, whereas birds remain for much longer
periods in a state of health when fed exclusively upon
the unpohshed grain. He also made use of the ob-
servation of Fraser and Stanton, that an alcohoUc
extract of rice poUshings would effect a ''cure'' of
polyneuritic birds. Funk made numerous elaborate
and painstaking attempts to separate the ''curative"
substance, and wrote extensively on what he believed
to be "deficiency" diseases. Under this term he
included beri-beri, scurvy, pellagra and rickets.
Hopkins discovered that small additions of milk
to food mixtures composed of purified protein,
carbohydrate, fats ^nd inorganic salts, rendered them
capable of inducing growth, whereas without such
additions no growth could be secured. The effects
t^ere out of all proportion to the energy, or protein
value of the added milk, and he suggested the exist-

84 THE NEWER KNOWLEDGE OF NUTRITION

ence of ^'accessory'' food-stuffs, which are required
in but small amounts, and which are absent from the
mixtures of purified food-stuffs, which fail to protiiote
growth. To the supposed ''curative'' substances,
.the presence of which in the diet prevents the develop-
ment of several syndromes enumerated, t'unk gave
the collective name ''vitamines." Thus he distin-
guished an antineuritic ''vitamine,'' an antiscorbutic
''vitamine,'' etc. These supposed substances have
since been variously designated as ''growth sub-
stances," "growth determinants," "food hormones,"
"accessory" food substances, etc.

McCollum and Davis through their studies with
diets of purified food-stuffs, pointed out that it was
highly probable that there are essential in the diet
but two substances rather than groups of substances
of imknown chemical nature, and it was shown, as
has been pointed out, that one of them is associated
with certain fats, while the other is never foimd with
the isolated fats of either anhnal or vegetable origin.
McCollum and Kennedy ^ suggested that they be
provisionally called fat-soluble A and water-soluble
B, because of their characteristic solubility in fats
and in water respectively.

The above terms, except the last two, are mis-
nomers. The word accessory, carries the idea that
the substances in question are dispensable. Con-
diments may be desirable, but they can be dispensed
with and are properly designated as accessory food
substances. An indispensable food complex cannot

"DEFICIENCY" DISEASES 85

properly be designated by this term. ''Vitamine''
is objectionable, because the prefix vita connotes an
importance of these dietary essentials greater than
other equally indispensable constituents of the diet,
such as certain of the amino-acids which play a role
in protein metabolism. The ending amine has a
definite and spe€ific meaning in organic chemistry,
being used to designate a compound derived from
ammonia by the substitution of one or more of its
hydrogen atoms by various organic radicals. Any
substance to be properly designated as amine must
contain the element nitrogen. There is no evidence
that either of these unidentified dietary essentials
is an amine, and indeed fat-soluble A probably con-
tains no nitrogen, for it is especially abundant in
butter fat, and the latter is practically free from this
element.

''Food hormones" is an objectionable term, be-
cause all the evidence available indicates that both
the fat-soluble A and water-soluble B are never-
failing constituents of the cells of both animal and
plant tissues. They have nothing in common with
the hormones. The latter are chemical substances
which are formed in the body by special tissues and
contributed to the blood stream where they cause
the stimulation of certain other tissues to physiolog-
ical activity. They are chemical messengers, while
the substances under discussion are food complexes,
apparently necessary for all the living cells of the
body. It has been pointed out that the content of

86 THE NEWER KNOWLEDGE OF NUTRITION

both of these two dietary essentials appears to run
parallel to the content of cellular elements in the
food-stufifs, regardless of their source.

'' Growth substances" and ^^ growth determinants"
are not good terms for the reason that the substances
in question are just as essential for the maintenance
of a full grown animal in a state of health as they are
for the support of growth in the young. Further-
more, in actual experience, rations are found in
which the content of one or more essential amino-
acids are present in such amounts that they form
the limiting factor which determines the value of the
ration. It is easy to prepare a food mixture in which
any one of the eight or nine essential inorganic
elements which the diet must furnish, will be so low
as to prevent the growth of an animal even though
the food is otherwise of satisfactory character. In
one case the addition of a suitable sodimn compoimd
or in another a calcium or a potassimn salt might
induce growth, and these elements might, with just
as much propriety, be called ''growth determinants"
as to apply this term to one of the still unidentified
food essentials. The term might fittingly be applied
to any of the indispensable components of the diet,
such as certain of the amino-acids, which result from
the digestion of the proteins.

All naturaHoodsStufifs, such as the seeds of p lants,
the leaf y vegetate s, fruits^^jmits, tubeis,^ meats,
eggs^^andmilk, contain fiftrt.fl.i n flmmmts of all the
substanc es which -a .r^ i^^^peng able com ponents of

I4|l|

11 1 ill

.9 is .2 -a -a %

itiill

a o ^ a ffl .ij .3

I III In

'3 § § ^9 I

* •

;

•/

"DEFICIENCY" DISEASES 87

the_diet. There is, however, great variation in the
gmlitji^otJ^he^^Ss^^ with re spect to the^ ev-

eral faetors. Some contain much protein, others
little, and a similar variation with respect to other
constituents is found. The special properties of the
several groups of food-stuffs have been described in
Chapters III and IV. ^

The best sources of fat-soluble A are whole milk y
butt er fat and ^gg y^^k fats and the leaves of plan ts. -^
The seeds of plants contain less and those products
derived from the endosperm of the seed are very
poor in this substance. Such food-stuffs as bolted
flour^ deger minated ^om meal, polished rice^ stajch,
glucqsejand the sngj^r^ fmir) iTiilkj cane^ and beet are
practicall y free from the fat-solu ble A. The specific
result of a lack of a sufficient amount of this sub-
stance in the diet is the development of a condition
of the eyes which appears to be rightly classed as a
type of xerophthalmia. The eyes become swollen
so badly that they are opened with difficulty or not
at all. The comea I||boi pp!s JTifli^. Tnftdj and unless
the missing dietary essential is supplied, blindness
speedily results. Osborne and Mendel ^ have also*
noted this condition in experimental animals and
its reUef by feeding butter fat. The introduction
into the diet of 5 or more per cent •of butter fat
will cause prompt recovery in cases where the an-
imals are within a few days of death. Complete* re-
covery takes place within two weeks if the sight has
not been destroyed. The normal condition of the

•

88 THE NEWER KNOWLEDGE OF NUTRITION

eyelids can be restored even after the sight is gone
and the cornea has faded.

When the diet consists principally of one of the
cereal grains such as the wheat, oat or com kernel,
or even a mixture of these, and it is satisfactorily
supplemented with respect to the inorganic elements
in which they are deficient, viz., calcium, sodium
and chlorine, and their proteins are enhanced in
value by the addition of a protein of good quaUty,
animals restricted to such a food supply may long
escape the onset of this disease. The seeds are not
enth^ly lacking in the substance, fat-soluble A.
They contain, especially the wheat and com kernels,
about haK the amoimt requh^ to maintain an
animal in a state of health. If the seeds or their
mixtures are supplemented with respect to but a
single dietary factor, e. g. inorganic salts, but the
protein content is left of relatively low biological
value, the debiUtating effects of the low value of the
food mixtm^ in the two dietary factors (protein and
fat-soluble A) simultaneously will hasten the onset
of xerophthalmia.^ When judging the effects of the
diet on an animal, it is necessary to take into accoimt
the fact that the diet is a complex thing, and that if
it is properly constituted with respect to all factors
but one an animal may tolerate it without apparent
injury whether the fault Ues in one or another of the
essential components. The value of one component
may fall well below that which will lead to serious mal-
nutrition, when a second dietary factor is likewise poor.

lisj^a

.ail^

' 1

identical except
per cent of butt
>il. The former
and emaciation,
graphed.

if these two rats were
I the right was ^ven 1.5
3f bleached cottonseed •
md suffered loss ot hair
ophthalmia when photo

3 -S 1 "S ■*

l||l|

^^^.<

||||l

^Hj-

weaning
they con
the Ht r
he latter
ehadnol

a-g e '^Ti

1^ ta s

« 1 J iT 1

Hill

■s-Sl.a

"DEFICIENCY'^ DISEASES 89

The idea should not be entertained th at-butter
fat is ijh e only food which supplies the fat-soluble j\.
If the diet contains a liberal amount of milk , eggs ,
glan dular o rgans or t he leaves of plants, ilj zdll, if
otherwise satisfactorily constituted, prevent the
onset of iihs.^gj^§-di3ease. The seeds and seed prod-
ucts, such as wheat flour (bolted), degerminated
com meal, polished rice, starch, the sugars, syrups,
tubers, roots, such as the radish, beet, carrot, turnip,
etc., and also the muscle tissue of animals, such as
ham, steak, chops, etc., do not contain enough of
the fat-soluble A to be classed as important sources
of this dietary essential. The tubers and ropts
appear jo be som e what ri ch^jin it than are the j^

seeds.^ In the forai in \dDich they are ordinarily
eaten, as mashed or baked potato, baked sweet
potato, fresh or creamed radish, cooked carrots,
beets or creamed turnips, the water content of the
dish as served is so high that the amount of soUds
eaten is not a very high per cent of the total food
supply, and the protective action is correspondingly
limited. In Americ^J^wever, potatoes are seldom
eaten without the adcfflon of butter. The vegetable
fats and oils such as olive oil, cottonseed oil, peanut
and cocoanut oils, although good energy yielding
foods, do not furnish this dietary essential. The
body fats of animals such as lard, beef fat, etc., are
not important sources of the fat-soluble A.

McCoUmn and his co-workers have repeatedly
observed in experimental animals the type of xeroph-

90 THE NEWER KNOWLEDGE OF NUTRITION

thalinia of dietary origin which has been described
above. They have many times rescued animals
from the threshold of death by the addition of
butter fat to the diets of the animals which were
suffering from the disease which was brought about
by a lack of a sufficient amoimt of the fat-soluble A
in their food. It is important to inquire whether ,
or not this disease has ever occiured in man. It is
not easy to decide from the descriptions, in the clin- f
ical literature, of the eye troubles of poorly nourished '*,
peoples in various parts of the world, which are of
the peculiar type with which we are now dealing,
and which are due to other causes. Soreness of the
eyes is conmion among many primitive peoples.
Herdlika ^ describes severe eye troubles among the
American Indians of the southwest, and attributed
them to too great exposure to strong simlight. In-
fection of the eyes is common among many peoples, ,
and the clinician, not being aware of the existence *
of a pathological condition of the eyes due to faulty
diet, would, of course, be inclined to attribute such
conditions to other causes.

There are several instances of the occurrence of
conditions described in the literature as xerophthal-
mia, which seem to be beyond question, cases in
which the disease has occurred in man as the result
of specific starvation for the dietary essential, fat-
soluble A. Mori ^ in Japan described in 1904, four- j
teen himdred cases of xerophthalmia among children
in a time of food shortage. He describes the condi-

liifl

"DEFICIENCY" DISEASES 91

tion in a xnanner which agrees closely with that which
McCoUum and Simmonds have observed in animals
whose diets were lacking in a sufficient amount of
fat-soluble A. The evidence that he was dealing
with this disease is made almost conclusive by the
.fact that he states that feeding chicken livers effected
a cure. It has been ajgeady mentioned jihat. the
glandulftT^organs con tain the fa t-solubl e^ A jn, fair ly
libera l amou nts. Th^Japanese have, as a rule, no
dairy products. Their diet consists of seeds and
seed products, roots, tubers, leaves and meats, prin-
cipally fish. Their principal sources of the dietary
factor in question are the l eafy vegetable and egg s, the
former of which in normal times they consiune much
larger amounts than do the peoples of most parts
of Europe and America. Shortage of food will occur
usually owing to drought, and the first products
which fail are the green vegetables, and accordingly
the dietary essential which would be least abimdant
would be the fat-soluble A. Mori attributed the
xerophthalmia to fat starvation. It seems highly
probable, however, that a lack of fat was not in it-
self the cause of the disease, but rather the lack of
the unidentified dietary essential which is associated
with certain fats, but is not furnished by any of the
isolated fats of vegetable origin, although it is present
in plant tissues where these contain cellular struc-
tures. Mori states that the disease does not occur
among fisher folk.
Bloch ^ has recently described forty cases of severe

92 THE NEWER KNOWLEDGE OF NUTRITION

necrosis of the cornea with ulceration, in the vicinity
of Copenhagen. The children had been fed nearly
fat-free separator skim milk, and were atrophic or
dystrophic and anemic. He attributed the disorder
to fat starvation, since the children responded with
recovery when fed breast milk, or in the case of older .
ones, with whole milk mixtures and to codliver oil
administration. The recovery, it will be noted,
followed the feeding of those substances which are
good sources of the fat-soluble A.

Czemy and Keller ^ describe a similar condition of
the eyes in children suffering from malnutrition as
the result of being restricted to a cereal diet.

It seems certain that these cases of xerophthalmia
should be looked upon as a '^deficiency disease''
not hitherto recognized in its proper relation to diet.
It is not a fat starvation, but, if it be the same condi-
tion which McCoUinn and Simmonds have definitely
shown to be readily relieved in its early stages by
the administration of such foods as contaia liberal
amounts of fat-soluble A, it would not be relieved
by feeding with vegetable fats in any amounts. ^litk, if
eggs, leafy jzege tables and tho pjlandular orpannj
are the foods which ^p^rve, to p^ntpfit flgamst a. short-
age of this inc^pensable dietary component. This Jlf
type of xerophthalmia is analogous to beri-beri, in
that it is due to the lack of a specific substance in
v^the diet. Beri-beri and xerophthalmia are according
^to McCollum and Simmonds, the only diseases refera-
ble to faulty diet, which are to be explained inthis way.

"DEFICIENCY" DISEASES 93

Beri-beri is a disease common in the Orient among
peoples who limit their diet largely to poUshed rice
and fish. It has, in recent years, been described in
La^borador owing to excessive consimiption of bolted
flour, ^ and in Brazil among laborers whose diets were
of varied character, but not judiciously chosen. ^°
Its most striking characteristic is a general paralysis,
and it is frequently referred to, especially when pro-
duced experimentally in animals, as polyneuritis.

The disease was first produced in animals by
Eijkman ^^ in 1897. He discovered that when
pigeons and chicEens were restricted to. a diet of
polished rice, they steadily lost weight and in time
came to manifest all the essential symptoms char-
acteristic of beri-beri in man. In pigeons the disease
usually appears in two or three weeks. He found
that feeding rice poUshings would produce a reUef
of the symptoms. This result suggested that there
was lacking from polished rice, something which was
necessary for the maintenance of health in the bird,
and that that something was present in the rice
polishinge. This was the first experimental evidence
that there is necessary in the diet substances other
than proteins, carbohydrates, fats and inorganic salts.

The observations of Eijkman attracted but Uttle
attention imtil Funk ^^ took up the study of beri-
beri in 1910. Fraser and Stanton had, as early as
1907, employed alcohoUc extracts of rice poKshings
for the cure of experimental polyneuritis. Funk
made numerous studies directed toward the isolation

94 THE NEWER KNOWLEDGE OF NUTRITION

and study of the substance which exerts the curative
effect, and developed in his writings the well-known
''vitamme'' hypothesis. This hypothesis postulated
the existence of a similar protective substance for
each of the diseases scurvy, pellagra and rickets,
in addition to that which in the normal diets pro-
tects against beri-beri.

Fimk had experimental evidence in support of his
theory only in the case of beri-beri. The evidence
that the other diseases which he included in the
category of ''deficiency'' diseases are due to the lack
of specific . complexes, was of the nature of clinical
observations, rather than well controlled experiments.
The peculiar value of butter fat was unknown to
him, and he classed it among the food substances
which contain no ''vitamine'' because its administra-
tion to polyneuritic pigeons produced no beneficial
effects. ^^ Fimk deserves great credit for the evidence
which he secured that the amount of the substance
which can be extracted from rice polishings, which is
necessary to cause the relief of polyneuritis in a
pigeon, is exceedingly small. A few milligrams of
material which is still contaminated with impurities
suffices to bring about relief in a bird which is in a
helpless condition and within a few hours of death,
and to make it appear like a normal pigeon. The
effects seem to be out of all proportion to the amount
of substance administered. Fxmk's studies were con-
firmed and extended by the important work of
WiUiams.i^

1l"8iiJI| li

2 §^ " s * a S »j

iiliill^ li

■a'S'5

!||t|i||SI

-.4

llllU^

"DEFICIENCY" DISEASES 95

There can be no doubt that there are two ''de-
ficiency'' diseases in the sense in which Funk and
his school employed this term. One of these is
beri-beri and the other the type of xerophthalmia
which McCoUimi and Simmonds have pointed out
as occurring occasionally in man as the result of
faulty diet, and have demonstrated to be the
same condition which results in aninaals as the re-
sult of specific starvation for the unidentified di-
etaiy essential fat-soluble A. It is of the greatest
importance to detennine whether scurvy, pellagra
and possibly rickets are likewise to be attributed to
the lack of similar substances of a specific nature in
the diet. It has already been mentioned in Chapter
II that from a knowledge of the dietary properties
of the oat kernel, McCollum and Pitz concluded
from a study of experimental scurvy in the guinea
pig, that this disease, while referable to faulty diet,
does not result from the absence of any special sub-
stance from the diet. The evidence upon which this
conclusion rests has been touched upon (page 36)
and will be next briefly considered.

The oat kernel, w hen submitted to the Jbiological
method of analysis described in the first chapter, was
found tcTcont ain all the ch emicaLelemei^t s and com-
ple xes ne ces^^^y for thf^ proinption of growth and
health uxjjnaiimaal, but not in suitable proportions.
Like other seeds it requires certain in^ganic addi-
tions, and its content of the unidentified f at-solubl e
A i s entirely too small to permit of growth, or to

96 THE NEWER KNOWLEDGE OF NUTRITION

protect an animal against the eye disease, xeroph-
thabnia. In addition, its proteins are not com-
parable in value with those of such foods as milk,
eggs and meats. The important fact was denaon-
strated by McCollum, Simmonds and Pitz, that
if the extracts of natural foods which we have long em-
ployed in our experimental work and which we desig-
naie water-soluble B, contain any physiologically in-
dispensable substance other than that which prevents
beri-beri, the oat kernel contains all of these. This
follows from the fact that they were able to induce
normal growth and prolonged well-being in animals
fed the oat kernel' supplemented only with purified
food substances f — ^viz: protein and inorganic salts,
and a growth-promoting fat. The latter term
is used to designate a fat containing the fat-
soluble A.

McCollum and Pitz observed that the guinea pig
suffers from scurvy, not only when restricted to a
diet of oats, as stated by Hoist, but likewise when fed
oats and all the fresh milk it will consume. Jackson
and Moore ^^ made this observation independently
and described it several months previous, in their
excellent studies of the bacteriology of the digestive
tract and tissues of the guinea pig, after the ardmals
have developed the disease as the result of an ex-
clusive oat and milk diet. Milk alone is a complete
food, and suffices for the maintenance of growth and
a good state of njijjltajb^n in several species of animals,
such as the rat and swine. It cannot, therefore, be

"DEFICIENCY" DISEASES 97

lacking in any imidentified food substance. Why,
then, should the guinea pig suffer scurvy when re-
stricted to a diet of oats and milk?

McCoUum and Pitz found in the guinea pigs which
had died of scurvy, that the cecum which is a very
large and very deUcate pouch through which the
food must pass in going from the small to the large
intestine, was always packed with putrefying feces. ^^
They decided that the mechanical difficulty which
the aninaals have in the removal of feces of an un-
favorable character from this part of the digestive
tract was in some way related with the development
of the disease. That this ass"umption was correct,
was shown by the fact that the administration of
liquid petrolatum, a ''mineral'' product to which no
food value can possibly be attributed, served to re-
lieve a certain nimiber of animals after they were
near death from the disease, while confined strictly
to the diet of oats and milk which caused them to
develop sciury. The explanation which they offered
was that the liquid petrolatum served to improve
the physical properties of the contents of the packed
cecum, and thus enable the animals to rid themselves
of this mass which was xmdergoing putrefactive de-
composition.

Further experiments showed that when the ani-
mals were fed an oat aad nailk diet, to which was
added suitable doses of phenolphthalein, a ca-
thartic, they could withstand the diet for long
periods without developing scurvy. This, accord-

98 THE NEWER KNOWLEDGE OF NUTRITION

ing to McCoJlum and Pitz, was due to the addi-
tional secretion of water into the digestive tract,
brought about by the cathartic, and resulted in
softening the feces so that they were naore easily
eliminated from the cecum.

It has long been known that o range juic e is a very
efficient protective agent against scurvy, both in man
and the guinea pig. In fact it was because of the
spectacular relief of the disease by the administration
of orange juice or of fresh vegetables, that Funk
was led to the belief that scurvy is, like beri-beri,
due to the lack of some specific chenaical substance
from the food supply. McCoUum and Pitz further
tested their theory by preparing an artificial orange
juice, in which every constituent was known, and
the administration of this to guinea pigs which were
confined to a diet of oats and milk, on which food
supply they almost invariably develop the disease.
The ''artificial orange juice ''consisted only of cit-
ric acid, cane sugar and inorganic salts, in about the
proportions in which these occur in the edible portion
of the orange. It was demonstrated that this mix-
ture exerted a decidedly protective action when added
to the oat and milk diet, and prevented the develop-
ment of scurvy over a loAg period.

Jackson and Moore suggested that scurvy is a
bacterial disease, and they have secured experimental
evidence which strongly supports that view. They
foimd in the hemorrhagic joints a diploccocus, which
may have a causal relationship to the disease. They

! ail 111

ja * a -a g 53 -a

s .a g ° S .9 1

j|5i||a

I ■' ' "

■3

IISS^

"DEFICIENCY" DISEASES 99

were able to induce mild symptoms of scurvy by the
injection of bacterial cultures into animals which
were fed upon a diet which regularly maintains the
guinea pig in a state of health. McCoJlum and Pitz
hold the view that there may be an invasion of the
tissues by organisms as the result of injuiy to the
cecal wall, when the animals are debiUfcated. The
cecum is injmed by long contact with the irritating
products formed by putrefactive bacteria acting on
the protein substances contained in the cecum when
it becomes packed with feces of such a character
that they cannot be eliminated. They suggested the
alternative hypothesis that there may be formed
through bacterial activity, substances which are
toxic, and have such pharmacological properties as
cause injury to the walls of the capillaries of those
areas in which hemorrhage is observed in sciu-vy.
There are several problems still to be solved in con-
nection with the cause of scurvy, but it seems to be
satisfactorily demonstrated that it is not a ''de-
ficiency" disease in the sense in which are beri-beri
and the type of xerophthalmia of dietary orgin. There
is, according to McCollum and his co-workers, no
protective substance against this disease. Diets of
faulty character, and especially bacteriologically un-
satisfactory, are responsible for its etiology, and it
is relieved by a satisfactory diet. The peculiar ana-
tomical structure of the aUmentary tract of the
guinea pig makes it difficult for it to thrive imless
its diet contains a succulent vegetable, which gives

100 THE NEWER KNOWLEDGE OF NUTRITION

the feces favorable physical characters and which
makes them easy of elimination.

Hess ^^ has recently described the results of his
observations on infants which were fed milk treated
in various ways, and these are of great significance
in throwing light on the cause of scurvy. He points
out that for a period of two years milk which had
been pasteurized commercially at 165° for thirty
minutes was employed in feeding the infants in his
charge. For two subsequent years the dealers raised
it to only 145"^ for thirty minutes. In his experience
the former milk was more likely to induce scurvy
than the latter. Hess thereafter secured raw cer-
tified milk and pasteurized it at the institution for
thirty minutes at 145."^ Infants fed this milk did not
develop scurvy in any instance, and one which
showed symptoms of subacute scurvy improved on
the home pasteurized milk. How did this milk differ
from the commercially pasteurized milk which did
show definite tendency to induce the disease? He
points out that it differed mainly in the interval
which elapsed between the time of the heating process
and the time of consumption of the milk. In New
York City, the greater portion of the bottled milk
sold is of Grade B, most of which is brought to the
city for pasteurization, which is done soon after mid-
night. Much of this is delivered to the consumer
the following morning, but a part is allowed to stand
until the following day before delivery. The city-
milk of Grade A was largely pasteurized in the coun-

" DEFICIENCY " DISEASES ,:;*:;.; 401

try, and since they stored the milk for twenty-four
liours after the heat treatment so as to insure a con-
stant supply in case of delay in the deUvery from the
country, there was an interval of forty-eight hours
between the pasteurization and the deUvery of the
milk to the consumer. Hess reproduced these con-
ditions in his institution by keeping milk pasteurized
at 145° for forty-eight hours on ice. Of eight in-
fants which were fed the milk so treated, two showed
scorbutic symptoms, which were relieved by giving
them orange juice. Two out of another eight which
were fed milk which was kept on ice forty-eight
liours after the heat treatment showed signs of
scurvy. In other cases scurvy was observed in
infants fed certified milk which had not been pas-
teurized, when the latter had been kept on the ice
forty-eight hours before feeding. Ageing is, therefore,
effective in causing changes in both raw and pasteur-
ized milk, so that the danger of the development
of scurvy in infants to which it is fed is increased.

Boiled milk has been extensively fed to infants in
various parts of the world and in the experience of
some observers does not induce scurvy. The expe-
rience of Hess further supports the view that boiled
milk is less liable to induce scurvy than is milk which
has been pasteurized at 165® or at a lower temper-
ature. Milk which has been pasteurized at 165° is
more liable to induce scurvy than either boiled milk,
or milk which has been pasteurized at lower temper-
atures, as 140-145® for thirty minutes. The most

i02 : tafc NEWEU KNOWLEDGE OF NUTRITION

satisfactory explanation for these results seems to be
found in the bacteriological condition of the milks
treated in the various ways described. Heating milk
at 165° kills nearly all the lactic acid forming bacteria
which normally cause the souring of milk. Heating
for thirty minutes at 140° to 145° leaves some of the
organisms capable of development, and milk so pas-
teurized will sour. In the absence of the acid formers
there develop during the interval between heating
and consumption the spore-forming organisms which
are not killed by pasteurization. These will, in time,
cause the putrefactive decomposition of the milk.
Any heat treatment which kills all the acid formers
leaves the milk in a suitable condition for the devel-
opment of the pernicious forms, and old milk so
treated may be a menace to the health of infants,
and unfit for consiunption by adults. Boiling tends
to destroy all the organisms in milk and will do so
if sufficiently prolonged. Such milk may be more
suitable for food than that which has been so treated
as to prevent souring and yet be in a condition to
permit the growth of putrefactive forms of bacteria.
These results strongly support the view that there
is a bacteriological factor involved in the causation
of scurvy, and emphasizes the importance of securing
clean milk, and of having it so handled as to insure
its delivery in a good bacteriological condition.
Milk should not be kept in the home without efficient
refrigeration, and should be consumed before it
becomes stale. Pasteurization seems, in itself, to

"DEFICIENCY" DISEASES 103

have little influence in lowering the food value of
milk. The staleness is the great element of danger.
Pasteurization is desirable as a safeguard against
such diseases as typhoid fever, tuberculosis, scarlet
fever and such organisms as cause epidemics of sore
throat. It does not render milk permanently harm-
less. The pubUc should insist upon having its milk
supply produced under hygienic conditions. Milk
should then be cooled promptly so as to depress as
far as possible the growth of the organisms which
always find entrance through the air and from the
cow and the milker. It should be carefully refriger-
ated, and promptly delivered and properly cared for
in the home, and should not be allowed to age un-
necessarily before use. If pastexirized, it should pref-
erably receive the lowest heat treatment which will
effectively destroy the pathogenic organisms, and
should be deUvered as promptly as possible there-
after in a suitably cooled state. Stale milk is danger-
ous, especially for use in infant feeding.

Pellagra. — This disease has been common in parts
of Europe for centuries. It is especially common in
northern Italy, and has been sometimes referred to
as Alpine scurvy. It is likewise known in Spain and
aad the south of France. The disease was first ob-
served in America in 1907, and has been steadily
on the increase, especially in certain of the Southern
States. In 1917 it was estimated that there were
165,000 pellagrins in the United States.

Pellagra is essentially a disease of poverty, al-

104 THE NEWER KNOWLEDGE OF NUTRITION

though there axe many cases recorded among the
well-to-do. It has been especially prevalent in the
country, in villages, and in the poorer sections of
cities, and is observed to occur most frequently
following periods of scarcity of food. In Europe
the disease was long associated with the consumption
of spoiled maize as the chief article of diet, but it is
now known that the eating of this grain has nothing
whatever to do with its causation. All observers
are agreed that the diet is of primary import in the
etiology of the disease, but differences of opinion
still exist as to whether there is likewise a bacteri-
ological factor involved.

The trouble begins with digestive disturbances of
an indefinite character, followed by soreness of the
mouth, which renders eating difficult, and a per-
sistent diarrhea which saps the strength of the pa-
tient. Skin eruptions appear, and there are formed
on parts of the body dark crusts which sometimes
suppurate. In severe cases there are pronoimced
nervous disturbances preceding death.
^ In its early stages pellagra yields fairly readily
to dietetic treatment. Indeed it has been emphasized
by clinicians that without dietary measures, there is
no effective treatment, and numerous cases are re-
corded in which the disease has disappeared promptly
when milk, eggs and meats, string beans, together
with a Uberal amount of the leafy vegetables, such
as cabbage, coUards, and lettuce, were included ia
the diet. 18

" DEFICIENCY ^^ DISEASES 105

In the United States, especially, pellagra tends to
seasonal occurrence, most new cases occurring in the
spring, or better, as Goldberger has emphasized,
at the end of winter. Jobling, in his excellent survey
of pellagra in Nashville, found that nearly all cases
had their onset in the spring and early summer. ^^
It frequently happens that sufferers recover from
their attacks of the disease during the later summer
and fall, and suffer a relaspe during the following
spring. Indeed the diet of many of the poorer people
of the South, during the winter, consists principally
of com brea d, pork and molas §£S. From what has
been* said in earlier chapters, it will be easily ap-
preciated th^t such a combination of food-stuffs does
not constitute an adequate diet, and it is significant
that nearly all new cases develop after a himdred
days or more of confinement to such a food supply.

It should be pointed out that Jobling and Peter-
son emphasize that from their observations the
pellagrins, and the class from which the new cases
develop, consiune relatively much carbohydrate and
relatively little protein, since they make liberal use
of com bread, com grits, and potatoes and biscuits
made from bdlted flour, together with molasses,
There were some who declared that they had regu-
larly eaten eggs, butter milk, milk and meat. They
further point out that in the spring, simmier and
autumn months a great deal of green stuff in the
form of turnip tops, wild mustard, green peas (seed)
and green onions are eaten. The green onions are

106 THE NEWER KNOWLEDGE OF NUTRITION

eaten raw, the others cooked. In addition, during
the summer months much fruit, especially peaches
and apples, are eaten since these are usually cheap.

In commenting upon the studies of Goldberger,
Jobling and Peterson point out that the poorly nour-
ished individual is prone to contract many diseases
and their observation that there is^a close relation-
ship between the sanitary condition of the different
parts of Nashville and the incidence of pellagra,
tends to strongly support the view that the disease
is associated with poor sewage disposal. The sani-
tary conditions in those districts where pellagra is
common are of the worst sort, in many instances
there being little pretense made of doing anything
with the excreta, which during the simmier is usually
covered with flies. Screening was usually absent
from those houses where the disease was found.
Jobling and Peterson are essentially in accord with
the conclusions of the Thompson-McFadden Comi-
mission ^ which made a thorough investigation of
conditions in Spartanburg Coimty, S. C, where
pellagra is a scourge, and arrived at the conclusion
that the disease is in some way related to a bacte-
riological factor, and is probably distributed by an
insect.

Golderger has accomplished a great work in demon-
strating that the diet, when properly constituted,
causes the disappearance of pellagra, and prevents
its recurrence. His dietary studies have demon-
strated beyond a reasonable doubt that a faulty

"DEFICIENCY" DISEASES 107

diet is the most important factor in causing the de-
velopment of the condition. He has shown that
when Uberal amoxmts of milk and eggs and of meat,
are mtroduced into the diet of institutions, such
as insane asylums and orphanages, in which the dis-
ease was previously common, they become free from
it even though new cases are admitted freely and
the sick are mingled with the well. He and his co-
workers have likewise made heroic attempts to
transmit the disease to themselves by means of the
administration of the excreta and material from the
lesions of pellagrins, but without success, when the
experimenters were taking a satisfactory diet.^i

An experiment on man, which was carried out by
Goldberger, is of special interest. A diet consisting
of dishes prepared from degerminated com meal,
bolted wheat flour, rice, starch, sugar, pork fat, to-
gether with sweet potatoes, cabbage, coUards, turnip
greens and coflfee, induced the appearance of what
were regarded as the incipient signs of the disease by
the end of five and a half months in five of eleven
men, who volimteered to submit themselves to this
dietary r^gime.^^

Chittenden and Underbill ^^ have described ex-
periments in which dogs were restricted to a diet of
crackers (wheat flour), cooked (dried) peas and
cottonseed oil. After intervals varying from two to
eight months, the animals developed the typical sore
mouth, severe diarrhea and skin changes strikingly
suggestive of pellagra in man. They were of the

108 THE NEWER KNOWLEDGE OF NUTRITION

opinion that this diet caused these symptonas be-
cause of the lack of some substance or substances of
the class designated as ''vitamines" by Funk.

McCollum, Simmonds and Parsons ^* demon-
strated that the diet of Chittenden and Underbill,
which consisted of bolted wheat flour, peas and
cottonseed oil, cannot be deficient in any other uni-
dentified dietary essential than the fat-soluble A, a
lack of which is associated with the development of
the eye disease, xerophthalmia. This conclusion is
necessary since rats were shown to fail to grow or
remain in a state of health, on this mixture, and that
it is rendered dietetically sufiiciently complete by
the addition of three types of purified food sub-
stances, viz., mineral salts, protein, and fat-soluble
A, to induce growth at the normal rate. The animals
failed, however, to successfully rear young. The
first limiting factor is the inorganic content. Every-
thing of an unknown chemical nature which the diet
must contain is present in a mixture of wheat flour,
peas and cottonseed oil, but there is a relative short-
age of the fat-soluble A, which is abundant in cer-
tain fats, and is associated with cellular structures
generally in both animal and vegetable food-stuffs.
McCollum, Simmonds and Parsons pointed out that
although their rats failed to maintain satisfactory
nutrition on this food mixture, unless the three
kinds of supplements were added, there was no
soreness of the mouth or diarrhea, such as was ob-
served by Chittenden and Underbill in dogs, and are

" DEFICIENCY *' DISEASES 109

usually present in pellagra in man. The eyes became
swollen when the diet was supplemented only by
salts.

An inspection of the diets described by Goldbei^er
as comrtion in those institutions where pellagra is
prevalent, and the winter diets of people in those
districts where there is a high incidence of the dis-
ease in the spring and summer months, shows that
these are composed largely of seeds and seed prod-
ucts, and the amoimts of leafy vegetables, milk,
eggs and meat, are very small, or are entiiely absent,
for varying periods. McCoUum and Simmonds ^^
have pointed out that in the experimental diet with
which Goldberger reported having produced incipi-
ent pellagra in man, about^i^ncty aix per cent of the [
total solids of the food supply was derived from seed
products: com meal, wheat flour, rice, starch, sugar,
molasses and from pork fat, and only about fom* per
cent from sweet potatoes and the leafy vegetables
l^np;pit}if>rr Such a Small amount of the leaf does not
suffice to make good the dietary deficiencies of the
seed products in such a diet. These deficiencies are
now well understood, and it is further known that
the tubers, such as the potato and sweet potato, are
not so constituted as to serve as ''protective" foods
when taken together with seed products. The diets
of those people who suffer from pellagra are, there-
fore/ deficient in three respects. They are relatively
low in protein and their proteins are of relatively
poor biological value, because they do not yield on

110 THE NEWER KNOWLEDGE OF NUTRITION

digestion, a favorable mixture of amino-acids for the
transformation into body tissues. They lack a
suflScient amoxmt of the unidentified dietary essential
fat-soluble A, and also of certain mineral elements.J|
The latter fault is in most instances limited to a
shortage of calcium, sodium and chlorine. Since it
is the regular practice of man to make additions of
sodium chloride in the form of table salt, to his diet,
the mineral deficiency in these diets may be said to
be limited to the element calcium. Any one of these
faults alone is sufficient to induce malnutrition when
either the young or the adult animal is restricted to
such diets as are common in pellagra stricken districts.
Since, however, there seems to be good evidence
that there sometimes occur cases of pellagra in in-
dividuals whose diets have included a certain amount
of such articles as McCollum and his co-workers
have designated as PROTECTIVE FOODS, viz.,
'milk, eggs and the leafy vegetables, the theory of
.an infection is supported. The prevalence of the
disease in badly sewered districts supports this view.
That there is a bacteriological factor involved in
pellagra is further supported in some degree by the
fact that McCollum, Simmonds and Parsong ^^ ob-
served only malnutrition without diarrhea or sore
mouth in rats fed diets which in the experience of
Chittenden and Underhill produce in dogs the gastro-
intestinal symptoms seen in pellagra in man. The
sloughing of the mucous membranes of the mouth,
and the presence of ulcers in the intestine affords

"DEFICIENCY" DISEASES 111

conclusive evidence of an infection in their dogs.
McCollum and co-workers found no unhealthy ap-
pearance in the mucosa of the digestive tract, even
when their rats were moribund as the result of being
fed only wheat flour, peas and cottonseed oil. It
seems probable that the diflference in this respect iq
the two species may well be attributed to a chance
infection in the one case which did not occm* in the
other. These observations are in harmony with the
fact that not everyone who takes the poor diets de-
scribed develops the disease. It seems logical in the
light of all the data available, to conclude that poor
nutrition predisposes to ii3fection, and that there is
an infectious agent involved in the production of
pellagra. There can be no reasonable doubt that
the possibility that pellagra is a '^deficiency" dis-
ease, in the sense in which Fimk employed this term,
is definitely answered in the negative by the ex-
perim^ital work of McCollmn and his co-workers.
If Rickets. — ^There can be no doubt that rickets is a
nutritional disease, but its relation to the diet is not
clear. It is characterized especially by an alteration
in the growth of the bones. These become enlarged
at the extremities and so soft that they bend imder
the stress of muscular contraction and under the
weight of the body. It is a disease of the first two
years of life, and is especially prevalent in children
in whose diet milk is replaced too largely by cereals
and other vegetable foods, not suited to the delicate
digestive tract of the young child. Predisposing

112 THE NEWER KNOWLEDGE OF NUTRITION

factors in many cases are undoubtedly tuberculosis
and syphilis. The symptoms develop gradually.
Restlessness and perspiration at night, great sen-
sitiveness of the limbs, that even a light touch is
extremely painful, are characteristic signs of the
disease. There are gastro-intestinal disturbances,
especially coUc and distension of the intestine with
gas, so that the abdomen protrudes. The bones
become thickened, and nodules develop at the junc-
tures of the ribs with the costal cartilages, forming
the characteristic '^beaded'' ribs. There is defective
ossification of the skull; the teeth appear later than,
normal and in unusual order. Various deformities
of the head, spine, chest and limbs result as the child
develops. Recovery with deforn^iity is of frequent
occurrence.

There must, at the present time, be an element of
speculation in any discussion of the relation of diet
to rickets. The well-known deficiencies from the
dietary standpoint of the cereal grains and the other
storage organs, together with the injury to the in-
testine, which is nearly always present, as shown by
the distended abdomen, and the occurrence of
rickets only in early life, and so frequently in associa-
tion with infectious disease, all make it unnecessary
to invoke the aid of any hypothetical '^vitamine,''
to a lack of which the disease may be attributed.

Hess ^^ has recently described the results of his
dietary studies among the negro women of the
Colmnbus Hill district in New York, whose children

"DEFICIENCY" DISEASES 113

almost all suffer from rickets. It is significant that
these women are attempting, like the very poor in
many cities, to Uve on a diet derived from the en-
dosperm of wheat, maize and rice, bolted flour,
degerminated commeal, polished rice, together with
tubers and meats. It will be evident from the data
furnished by the appUcation of the biological method
for the analysis of food-stuffs, which McCoUum and
his co-workers have perfected, and which was de-
scribed in Chapters I to III, that there are no com-
binations of those food-stuffs whose functions are
those of storage organs, which will constitute a satis-
factory diet for growth. Muscle tissue does not tend,
except in respect to the protein factor, to correct the
dietary faults of such mixtures. The regular con-
sumption of such diets will in the course of a few
months cause a distinct lowering of the vitality of
an adult and will cause even greater injmy to the
young child. In a later chapter it will be shown that
the milk of mothers taking such diets does not
satisfactorily nourish the young.

What has said/been above regarding the special
dietary properEies of the different food-stuffs which
go to make up the diet of civilized noan, and the
dietary habits of those classes of people who suffer
from the diseases which have come to be recognized
as being due to faulty diet, make it easy to see that
there has become fixed in the minds of students of
nutrition and of the reading public, an altogether
extravagant idea regarding the importance of the

114 THE NEWER KNOWLEDGE OF NUTRITION

substances to which Funk gave the name *' vita-
mines." Of the diseases which Fxmk considered due
to lack of unidentified substances of this nature,
viz., beri-beri, scurvy, pellagra and rickets, but one,
beri-beri, has been shown to be due to this cause.
In the course of the analysis by McColliun and Davis,
of the problem of what chemical complexes are nec-
essary to constitute the simplest diet which will
serve to support growth in the young, and maintain
physiological well-being in the adult, a second dietary
''deficiency'' disease in the same sense as beri-beri,
was discovered, and shown to have occurred sporad-
ically in man. This is the type of xerophthalmia
which results from a deficiency of the dietary essen-
tial of imknown checfiical nature, fat-soluble A.
Beri-beri is due to the lack of the second unknown
dietary essential water-soluble B. Pellagra, scurvy
and rickets do not belong in the same category with
beri-beri, and there do not exist ''curative" sub-
stances of unknown nature for these diseases. The
individual is predisposed to the development of these
syndromes by faulty diet, but the faults have been
shown by the biological method for the analysis of
the individual food-stuJBfs or their mixtures, to reside
in maladjustments, and imsatisfactory quantitative
relationships among the now well-recognized con-
stituents of the normal diet. They are to be sought
in the quaUty and quantity of the protein, the char-
acter and amount of the inorganic constituents, the
physical properties of the residues which are left

"DEFICIENCY" DISEASES 115

after digestion, and form the feces from which the
intestine must rid itself. It seems probable that
the only imidentified substance which is physiolog-
ically indispensable, which is not sufficiently abun-
dant in the diets employed by the people of the
United States and Europe where there are used in-
suflScient amounts of joiilk, butter, cream, eggs and
the leafy vegetables, is the fat-soluble A, but occa-
sionally diets may be met with which contain too
little of the water-soluble B. Sufficient knowledge is
now available to make it possible to select such foods
as will mutually make good each other's deficiencies,
and to combine them in such proportions as will
insure the disappearance of all the diseases of man
which are brought on by faulty diets. The same
knowledge will, in the future, make possible an
eflScient utiUzation of feeding-stuffs for animal pro-
duction, which will be of inestin[iable economic
value to naankind.

CHAPTER VI

THE NURSING MOTHER AS A FACTOR OF SAFETY IN THE

NUTRITION OF THE SUCKLING

Anyone who reflects upon the relation of the
mother to her young during the suckling period,
must marvel at the fact that during early life the
young mammal cannot thrive on the diet of the
adult. It must have milk for a shorter or longer
period after birth. This the lactating animal is able
to form from her food through the agency of the
mammary gland. The period of dependency varies
greatly in different species. Among mammals,
with which the author is familiar, the young guinea
pig is bom in the most highly developed state. The
newborn cavy is capable of eating grass or succulent
vegetables during the first or second day of post-
natal life. The young rat may be safely weaned at
the age of twenty-five days, provided a highly satis-
factory diet of the type which sufficies for the adult
is then supplied. The young pig (swine) becomes
able to eat fairly Hberally of the normal adult diet
at the age of six or eight weeks, whereas the human
infant must Uve largely on a milk diet during the
first year of life and should have a liberal allowance
of milk and of eggs during the entire growing period.

116

ill
fi

ifil!

THE NURSING MOTHER 117

Even eggs will not entirely replace milk during any
part of this period. It is of great importance that
we should imderstand the relationship between the
character of the diet of the lactating femiale, and the
quality of the milk which she is able to produce.
Our knowledge of this subject is still very incomplete,
but experimental studies on animals have recently
thrown light on certain very important phases of
this problem.

In order to gain information on the relation be-
tween the character of the diet of- the mother and
the value of the milk which she produces, McCoUum
and Simmonds ^ carried out a series of experiments
on lactating rats, whose diets were faulty in known
ways, and observed the effect on the growth of the
yoimg which these mothers nursed. The mothers
were fed a highly satisfactory diet until they had
completed their term of pregnancy. As soon as the
yoimg were born, the litter was in all cases reduced
to four, in or<jer that the nutritive imdertaking of
the mother should in no case be burdensome. The
mother was at once restricted to a diet which would
not induce any growth whatever in a yoimg rat after
separation from the mother at weaning time. The
diets of the mothers in the various experiments were
faulty in respect to each of the factors which are
necessary for the formation of a satisfactory diet,
but the nmnber of characters in which a single diet
was faulty varied from one to three.

In one case the mother was fed upon a diet of

118 THE NEWER KNOWLEDGE OF NUTRITION

purified protein, carbohydrate (dextrinized starch),
a suitably constituted inorganic salt mixture, and
an alcoholic extract of wheat germ to furnish the
unidentified dietary essential, water-soluble B. This
diet contained everything necessary for the nutrition
of a young rat during growth, except the fat-soluble
A. The problem was to find whether the mother
could, through the agency of the manunary gland,
form the missing substance, fat-soluble A. Expe-
rience has shown that the yoimg animal after the
weaning age, cannot produce it de novo, for its own
preservation from any of the other constituents of
its food. The results of the experiment indicated
that the quantity of the fat-soluble A in the nailk
produced ffom such a diet is below the amount
necessary for the promotion of the maximum rate
of growth in the yoimg. It has been shown by
Osborne and Mendel,^ that the body fats of beef
cattle contain a small amount of the fat-soluble A.
It seems certain that the body fats, of an animal
which has been fed for some time on a diet rich in
this substance, will serve as a reserve supply of this
dietary essential, which the mother can secrete into
the milk. In other experiments. Chart 15, definite
evidence is presented that this substance is not
abundant in the milk imless it is present in the diet
of the mother. The presence of some fat-soluble A
in the tissues of the mother makes it especially diffi-
cult to obtain milk which is entirely free from this
Lce.

THE NURSING MOTHER 119

Through similar experiments with diets which
contained the fat-soluble A, but not the water-
soluble B, evidence was secured that for a time the
mother is able to secure this dietary factor from her
reserve supply, but none of the growth curves in-
dicated that the substance is present in the milk
in adequate amount when the diet of the mother
lacks it. It seems certain that neither of these
substances is present in abimdance in the milk of
the mother, unless it is furnished in her food.

Evidence confirmatory of this view is found in
the studies of Andrews ^ on infantile beri-beri. It
is well known that the faulty diet of rice and fish,
which furnishes the principal food of many of the
poorer classes of the Orient, does not prevent the
onset of beri-beri, and infants who nurse mothers
who are suffering from the disease, likewise develop
beri-beri. Andrews induced several Filipino women
whose infants had just died of beri-beri, to nurse
young pups, and noted that in all cases the lat-
ter failed to grow, became edematous, and lost
the use of their hind legs. Paralysis of the posterior
extremities is one of the symptoms of the disease in
man. It is evident that in the milk of these mothers
there was a shortage of the water-soluble B, for it
is a shortage of this substance which causes the
development of this syndrome.

It has been pointed out that yoimg animals do
not grow when confined to a single seed or mixture of
seeds of plants, for the reason that these are all

120 THE NEWER KNOWLEDGE OF NUTRITION

lacking in sufficient amounts of the inorganic el-
ements, calcium, sodium and chlorine, and are too
poor in the fat-soluble A to support normal nutrition.
The quality of their proteins is likewise too poor
to make them very satisfactory for the support of
growth. McCoUum and Simmonds have studied
the* extent to which the mother is able to produce
milk of satisfactory character for the promotion of
growth in the young, when confined to a single seed as
the sole source of nutriment. Charts 15 and 16 show
the effects of such diets on the growth of the young.
The curves of rat 211 and of her Utter of four
young (Chart 15) illustrate the remarkable growth
which a mother rat is able to induce in her young
when her diet is highly satisfactory, and while
doing so, she is able to increase her own weight very
appreciably. In marked contrast to this /'normal''
accompUshment stands the failure of rat 738 to in-
duce more than one-third the normal rate of growth
in her young when restricted to rolled oats as her
sole food supply. The drop in the curve of the
yoimg at the 40th day was the result of the death
of the yoimg at brief intervals. The mother lost
weight regularly, showing that she was sacrificing
her own tissues for the preservation of her young.
Rolled oats, like the other seeds, require improve-
ment in respect to three dietary factors before it
becomes a complete food, and on such a faulty diet
the mother produces milk which is not satisfactory
for the promotion of growth in her offspring.

THE NURSING MOTHER 121

Rat 843, whose diet consisted of rolled oats sup-
plemented with fat-soluble A (as butter fat) induced
growth in her young at a somewhat greater rate than
she could have done, had she eaten oats alone, and
was able to keep them alive for a longer period.
The first one died on the 57th day and the others
followed in rapid succession. This mother lost con-
siderable weight up to the time that the young began
to eat of the oat and butter fat diet. Young rats,
after removal from the mother, cannot grow at all
on this diet.

Rat 899, was fed a diet of rolled oats to which was
added such an inorganic salt mixture as made good
the mineral deficiencies of the oat kernel. Her diet
was still deficient in fat-soluble A, and to some extent
in the quality of its proteins. With this food her
milk was oi distinctly better quality than that which
caxi be produced on a diet of oats alone, or on oats
supplemented with fat-soluble A, or on oats supple-
mented with pm-ified protein (rat 948) . From these
results it is apparent that the first limiting factor
of the oat kernel for milk production in the lactating
animal is the same as in the yoimg for growth, viz.,
the inorganic content of the food supply.

The importance of having the inorganic content
of the diet properly constituted is shown especially
well in the performance of the mothers 983 and
1978. The former was fed rolled oats supplemented
with both fat-soluble A, in the form of butter fat,
and pm-ified protein in the form of casein of milk.

122 THE NEWER KNOWLEDGE OF NUTRITION

Even with these two additions she was able to induce
less than half normal growth in her young and they
began to die at the age of 45 days, and all succumbed
in rapid succession. Rat 1978, on the other hand,
whose diet consisted of rolled oats supplemented
with a suitable salt mixture and butter fat, was able
to induce growth in her young at about two-thirds
the normal rate. The improvement of the milk
by the inclusion of fat-soluble A in the diet is very
apparent, since the young did not die during the
period of sixty days covered by the experiment, and
supports the view that this substance cannot be
synthesized by the mother.

Rat 1019, whose diet consisted of rolled oats
supplemented with purified protein and a suitable
salt mixture, shows that the mother is able to induce
nearly the optimum rate of growth in her young dur-
ing a period of thirty days, although her diet was very-
poor in the factor fat-soluble A. It should be borne
in mind that the seeds, because they contain a sncLall
proportion of cellular structures in addition to their
reserve food package in the endosperm, contain a
small but inadequate amount of the fat-soluble A.
The mother is able, when the diet of oats is corrected
with respect to two factors, protein and salts, to
concentrate in the milk the small content of the fat-
soluble A which her diet suppUes. She is probably
also able to draw in some degree upon her small
store of this substance which is deposited in her body-
fats, and supply the young with enough of it to

THE NURSING MOTHER 123

enable them to reach a state of relative mdependence,
which in a wild state would enable them to go in
search of food for themselves. There is abundant
experimental proof that when the protein and in-
organic content of the food are of highly satisfactory
character, animals can subsist for a long period on a
supply of fat-soluble A too small to prevent the onset
of xerophthalmia in diets of lower biological value.

These records of nursing mothers and their young
make it apparent that the former is limited in a
general way in the utilization of food for milk pro-
duction, in the same manner as in the growing young
in the utilization of food for the, construction of new
body tissues. She is, however, a factor of safety for
her young in no small degree. It should be remem-
bered that a young rat cannot grow at all when,
after the weaning age, it is limited to the oat kernel,
or to the oat kernel supplemented with either salts,
protein or fat-soluble A alone, or on a diet of oats
supplemented with both protein and fat-soluble A.
In order that it may grow even very slowly it is
essential that both a suitable salt mixture and fat-
soluble A shall be added to the oat kernel. It can-
not grow normally unless the protein factor is hke-
wise improved. In the records of the mothers and
young shown in Chart 15, the young continued to
grow in certain instances after the twenty-fifth day,
the age at which they may be safely weaned when
their milk supply has been of normal composition.
This fact is conclusive evidence that even after the

124 THE NEWER KNOWLEDGE OF NUTRITION

young become able to eat of the diet on which the
mother had produced the milk on which they were
able to grow — a diet on which they would be imable
to grow at all without some corrections and improve-
ments — they were still receiving a supplementary
milk supply from the mother. This served to correct
in some measure the faulty diet of oats plus an in-
complete supplementary addition. It seems certain
that milk production must have been very con-
siderable in amount, to thus enhance the diet of
four young whose weight collectively was about half
that of the mother herself.

The inorganic content of all the seeds is the first
limiting factor in preventing growth in yoimg ani-
mals, and in determining the quaUty of the milk which
can be produced from them. The young animal
cannot grow at all on seeds xmless one of the factors
corrected includes certain salt additions, yet the
mother is able to produce milk without any such
additions, which is capable of inducing a limited
amount of growth in the young. It is apparent that
one of her most important relations to her helpless
offspring is her capacity to supply it with a better
inorganic food supply than she herself secures in her
food, when the latter is of poor quaUty.

The growth ciuves of the young of mothers whose
diets consisted of the oat kernel without and with
purified food additions, illustrate Ukewise very well
the results which are observed when similar ex-
periments are conducted with the wheat or maize

THE NURSING MOTHER 125

kernel. They emphasize the fact that for milk pro-
duction as for growth, the seeds of plants may be re-
garded as closely similar in their dietary properties.
It is therefore, rendered highly probable that the
same analogy runs through the series of food-stufifs
in their value for the production of milk of normal
character. We are not to expect, therefore, that a
diet consisting of even a complex mixture of seeds,
tubers and roots, will produce milk of highly satis-
factory character, and without undue strain on the
mother. It has been emphasized that even this Ust
of foods of the class whose fimctions are those of stor-
age organs, do not.sufl&ce even when combined with
meat, to induce satisfactory growth in the young.
It follows as a logical conclusion, that a lactating
mother will not be able to produce milk of a very sat-
isfactory character when she is restricted to such
food-stuffs. It should be reiterated that there are
two classes of food-stuffs which are so constituted as
to correct the deficiencies of seeds, tubers, roots and
meat. These are milk and the leaves of plants and
they should be used very liberally in the diet. Eggs
are in some degree to be regarded as comparable to
these, but eggs have not the favorable mineral con-
tent of the leaves and of milk, and this is one of the
most important factors in which the storage organs
of plants need supplementing.

The question will arise in the minds of many, as
to whether the inabiUty of the yoimg to grow on the
milk produced by mothers which were Uving upon

126 THE NEWER KNOWLEDGE OF NUTRITION

an inadequate diet, was not the result of the failure
of the mothers to produce enough milk rather than
milk of abnormal composition. It has not been
foimd possible to seciu-e complete information as to
the actual amoimt of milk which these rats secreted,
but we have analogous data from domestic animals,
which support the view that milk secretion remains
fairly constant in the lactating animal even imder
very unfavorable conditions of nutrition.

Babcock ^ has described experiments in which he
deprived cows of common salt during lactation,
other than that which they secured in their regular
ration, which was of a type suitable for the dairy
cow. The keen appetite of the herbivora for salt is
a matter of common knowledge. Deer which are
very shy will risk any danger to secure salt at their
accustomed Ucks or from salt springs. The periods
of salt deprivation varied from two to fifteen months,
and some of the animals actually died, and others
were saved from death by the administration of salt.
In no instance was there a notable decrease in the
yield of milk by these cows up to a short time be-
fore they began to fail rapidly. Indeed the fat con-
tent of the milk of the cows receiving an inadequate
salt supply was slightly higher than in the milk of
the control group.

Eccles and Palmer ^ have conducted a very thor-
ough experimental study of the influence of imder-
feeding of cows on milk production, and have studied
its composition in cows whose rations were of suitable

THE NURSING MOTHER 127

composition, but inadequate in amoimt. These
results show that cows were able, during the early-
part of the lactation period, to maintain the milk
flow imdiminished for forty days, when receiving
but 75 per cent enough food to meet her require-
ments. Under such conditions of nutrition there
was no pronoimced change in the composition of the
milk. During the latter part of the lactation period
there was some falling oflf in milk production as the
result of imder-feeding.

Ducaisne ^ in 1870, noted that during the siege of
Paris, yoimg and vigorous women were able to pro-
duce enough milk to maintain their infants, and in
some cases to increase their weight when they were
partially fasting. These observations, as well as
those of Andrews on women whose infants had died
of beri-beri,^ all support the view that under con-
ditions of faulty nutrition, it is the quality of the
milk rather than the quantity which early suffers
impairment. Dr. Manuel Roxas, of the College of
Agriculture of the PhiUppine Islands, has informed
the author in a private communication, that the in-
fants' death rate among the natives is much higher
in the breast-fed than among the bottle-fed children.

The occurrence of mfantile beri-beri, rather than
of death from starvation, further serves to demon-
strate that it is milk of poor quality, rather than
lack of sufficient amount of milk which is responsible
for the high mfant mortaUty m those parts of the
world where the poorer classes live too largely on

128 THE NEWER KNOWLEDGE OF NUTRITION

food-stuffs derived from products whose biological
functions are those of storage organs, and naeat.

The statement which one sees reiterated so fre-
quently, that breast feeding of infants is superior to
the best system of artificial feeding, need^ to be
qualified to some extent. There are, without ques-
tion, in many parts of the world, large groups of
people whose diets are of such a character that the
quality of the milk produced by the lactating mother
is not such as to make it a satisfactory food for their
infants. It should be thoroughly appreciated that
the human mother should have in her diet a liberal
amoimt of milk in order to safeguard the health and
well-being of her infant, and of leafy vegetables,
which serve the two-fold function of a protective
food and of greatly aiding intestinal elimination.
That some mothers can induce a fair amoimt of
growth in their infants while taking a faulty diet,
cannot be denied, but that both mother and child
suffer impairment as the result is beyond question.
It is not enough that the diet shall furnish enough
calories and enough protein, and shall afford variety
and palatabiHty. The peculiar dietary properties
of the food-stuffs which enter into the diet are of
paramoimt importance, and must be taken into con-
sideration.

Attention should again be directed to the observa-
tions of Hess^ that the diet of the negro women of
the Colmnbus Hill district in New York, whose diets
are derived almost exclusively from seed products,

THE NURSING MOTHER 129

tubers and meats, fail to nourish their infants satis-
factorily as shown by the almost universal prevalence
of rickets among the latter. It is difficult for man
to correct the dietary deficiencies of these products
by the use of the leaves of plants as his sole protective
food, because of the limited capacity of his digestive
tract. Milk in liberal amounts should always be
included in the diet of the lactating mother.

CHAPTER VII

PRACTICAL CONSIDERATIONS WHICH SHOtjLD GUIDE IN

THE PLANNING OF THE DIET

In the preceding chapters there were presented
data, which have been obtained by biological
methods, concerning the special dietary properties .
of the several classes of natural food-stnfifs, which
enter into the diets of man and animals. It is evident
from the experiments described that a diet may fur-
nish an abundance of protein and energy, and may
be easy of digestion, and may furnish a wide variety
and include several seeds or products derived from
these, together with tubers, roots and meats, and
may be highly acceptable to the human palate and
yet fail utterly to support satisfactory nutrition.
In the Ught of such facts, it becomes apparent that
a chemical analysis of a food-stuff throws no Ught
whatever upon certain aspects of its dietary prop-
erties. It is only by biological methods that we can
arrive at principles which can serve as a safe guide as
to the method of procedure by means of which safe
diets can be planned. In the present chapter will be
discussed a number of questions which always arise
in the minds of those who wish to apply the new
knowledge to the planning of a suitable dietary
regime.

130

THE PLANNING OF THE DIET 131

It should be understood that it is neither necessary
or desirable that we should abandon the customary
classification of food-stufifs on the basis of chemical
composition. We must have a language of nutrition,
and consider foods on the basis of their protein,
carbohydrate, fat, water and mineral content, as we
have always done. We should be familiar with the.
quota of energy available from the different types of
foods. We must, however, take into consideration

rtain facts which have not hitherto been considered,
and concerning which a chemical analysis gives no
information.

One of the outstanding results of modem research
in nutrition is the great difference in the biological
values of the proteins from different sources. In a
general way this is appreciated by all well informed
teachers of the present day, but many are still in
need of clearer distinctions regarding what data in
the literature are capable of direct application to
practical nutrition, and what are of such a nature
that they cannot be so applied. No lack of apprecia-
tion is intended of data of the latter type, for tjhey
may have, and indeed frequently have a value of
the first importance to the investigator in this field.
A3 an example may be cited the laborious studies
through which the ammo-acids became known, and
the data yielded by such method of analysis of the
proteins as those of Fischer and of Van Slyke. Im-
portant as are these results in making possible fur-
ther progress, they are not of such a character that

132 THE NEWER KNOWLEDGE OF NUTRITION

they can be applied, as has been frequently at-
tempted, in making deductions concerning com-
parative food values. It is, however, through such
studies that we have arrived at a satisfactory working
hypothesis concerning the natiu-e of the proteins,
and have become able to appreciate why the proteins
have different values in nutrition. Our analytical
methods do not make possible an approximately
quantitative determination of more than a third of
the total nimiber of the digestion products of the
proteins. An attempt to utilize the figures for the
yield of this or that amino-acid by one or another of
the proteins, as evidence of the comparative values
of the proteins themselves, or of the food-stuffs from
which they are derived, will lead to entirely fallacious
deduction.

Such data as are tabulated in the literature for the
yields of the different amino-acids, make the pea
and bean proteins appear superior to those of the
cereal grains. McCoUum and Simmonds have re-
ported a long series of experiments with diets so
planned that they were adequate in all respects,
and the protein content was derived entirely from a
single seed. The amount of protein in the diet was
varied so as to find in one series what was the lowest
per cent of protein in the food mixture which would
just maintain a grown rat over a period of several
months without loss of body weight, and in another
series, the minimum amount of protein was deter-
uiined which would induce in the young, half normal

THE PLANNING OF THE DIET 133

and full normal rate of growth respectively. The
data regarding the values of several of the more im-
portant seed proteins for maintenance are of great
interest. Rats can be maintained in body weight
on suitably constituted diets containing 4.5 per cent
of oat protein, or of millet seed protein; on 6 per cent
of maize, rice or wheat proteins ; on about 8 per cent
of flax-seed protein, whereas it requires about 11 to
12 per cent of the proteins of the pea or the bean to
accomplish the same result.

Chemical analysis shows the proteins of the pea
and bean to contain all the known amino-acids,
and none of these are present in excessive or in min-
imal quantities, whereas the wheat and maize pro-
teins yield excessive anaounts of one of them in par-
ticular. Glutamic acid, one of the digestion products
of proteins, is present in the proteins of the muscle
tissues of animals, in the case of no less than half a
dozen species, to the extent of twelve to fourteen
per cent. The same acid is present in the two prin-
cipal proteins of the wheat kernel to the extent
of nearly 40 per cent, and in the principal protein
of the maize kernel to the extent of about 25 per
cent. These proteins show other differences in com-
position which led to the beUef that they were of
relatively low biological value for growth, before
they were studied satisfactorily by appropriately
planned feeding experiments, all of which have con-
firmed this view. The observation that the spUt
pea and navy bean proteins are of much less value in

134 THE NEWER KNOWLEDGE OF NUTRITION

nutrition came therefore as a distinct surprise, since
these results were not what were expected, in view
of the tabulated yields of the several amino-acids
shown by the most careful chemical analysis. The
data obtained by properly planned feeding experi-
ments are highly reliable, those from the chemical
analysis very imsafe, from which to draw deductions.
It should be "understood that these values for the
proteins of the seeds apply only to the proteins of
the single seed when fed as the sole source of protein.
When fed in mixtures of two or more proteins having
individually low values for the support of growth, they
may mutually make good each other's amino-acid
deficiencies, and form a mixture which is better than
either constituent when fed singly. Since this was
to be expected, McCollum, Simmonds and Parsons
have made many feeding trials with simple com-
binations of two seeds, such as two cereal grains, one
cereal and one legume seed (pea, bean) ; one seed and
one leaf, etc., as the sole som'ce of protein in the diet,
and have sought to find which are the most fortunate
combinations of the most important food-stuffs for
the production of protein mixtures of high biolog-
ical values for the support of growth. These trials
have shown that, while such mixtures of proteins are
superior to the individual foods fed separately as
sources of protein, it has not been found possible to
obtain protein mixtures from vegetable sources which
even approximate the value of milk proteins, for the
support of maintenance or growth.

THE PLANNING OF THE DIET 135

The nitrogen-containing compounds of the potato
have been lauded by several investigators as being of
extraordinary value as a source of protein. Mc-
CoUum, Simmonds and Parsons have studied the
proteins of the potato, both for maintenance and
growth, m experiments m which this tuber served as
the sole source of protein, and all its dietary defi-
ciencies were made good by suitable additions of
purified food substances. These all indicate that
when fed as the sole source of protein, the nitrogen
compounds of the potato have a distinctly lower
value than have the proteins of the cereal grains,
oat, wheat, rice and maize.

Enough has been said regarding the great dif-
ferences m the values of the protems from different
sources, to make it clear that it is impossible to say
how much protein the diet should contain without
having a knowledge of the values of the proteins
which the diet contains. Chemical methods of
analysis are not yet sufficiently perfected to throw
any appreciable light on the values of the mixtures
of proteins which occur in our natural foods.

The great attractiveness of the ^'vitamine" hy-
pothesis of Funk, as an explanation for all the states
of malnutrition which are referable to faulty diet,
has led, in recent years, to much discussion of the
question of the possible deterioration of foods during
cooking, canning and drying. The demonstration
by McCoUum and his co-workers that there are but
two unidentified dietary essentials, and but two diet-

136 THE NEWER KNOWLEDGE OF NUTRITION

ary ''deficiency'' diseases, due respectively to a
shortage of one or the other of these substances, fat-
soluble A and water-soluble B, and that there are no
''growth determinants" unnecessary for the mainte-
nance of health in the adult, does not minimize the
importance of this subject. The work of a nimiber
of investigators has shown that the water-soluble B,
the protective substance against beri-beri, is readily
destroyed when an excess of even such weak alkalies
as soda are added to, the food, suggests that this
substance may be of an unstable character.

Osborne and Mendel ^ have shown that butter
fat may have a blast of steam passed through it for
two hours and stiU retain its pecuUar growth-pro-
moting properties, due to the presence of the fat-
soluble A. This observation is in harmony with
those of McCollum and Davis, that heating butter
fat at the temperature of boiUng water does not
affect its peculiar dietary value. It is apparent,
therefore, that any conditions to which milk fats are
Uable to be subjected during the cooking of foods
will not greatly alter its value as a source of the fat-
soluble A. McCoUimi and Simmonds have recently
(unpubUshed data) tested a sample of butter fat
prepared from evaporated milk, furnished to them
by Dr. Lucius P. Brown of New York City, and have
found it very effective in reUeving the xerophthahnia
in rats, brought on by the lack of the fat-soluble A
in their diets. It appears, therefore, that there is no
great deterioration in the quahty of milk fats brought

THE PLANNING OF THE DIET 137

about by the processes of removal of water in the
preparation of condensed or evaporated milks. They
have likewise shown, as have also Osborne and Men-
del, that dried milks still contain the fat-soluble A
in abundance. There can be no serious objection to
the use of dried or canned milks on the basis of their
value with respect to this dietary essential.

The situation is likewise quite clear with respect
to the ordinary dried foods. Leaves such as celery
tops and those of the immature alfalfa plant, when
dried in the ordinary way, are still good sources
of the fat-soluble A. The alfalfa leaves were dried
in the sun and the celery tops by artificial heat in a
current of air after a preliminary treatment with
steam.

McCollmn and Davis ^ have pointed out that
wheat genn can be moistened and heated in an auto-
clave at fifteen pounds pressm-e for an hour or more
without any extensive destruction of the water-
soluble B, and McCollum, Simmonds and Pitz ^ have
subjected soaked navy beans to similar treatment
without causing any great deterioration with respect
to this dietary factor. This treatment is comparable
to that to which fruits and vegetables are subjected
when processed in canning, and shows that the wide-
spread beUef that canned foods have lost these diet-
ary essentials is, at least, generally without foun-
dation. The cooking of beans or greens with the
addition of soda, which is a common practice, may
cause the destruction of one or both of the unidentified

138 THE NEWER KNOWLEDGE OF NUTRITION

dietary essentials. At least in the case of the water-
soluble B, this will probably be true if sufficient
soda is added to render the food alkaline. The use
of soda in biscuit making will, according to Voegtlin,
and Sullivan ^ cause the destruction of the water-
soluble B, for they found that com meal cooked with
soda was no longer effective in causing the "cure'*
of beri-beri in pigeons.

In this connection it should be borne in mind that
our ordinary foods all contain several times the
amount of the water-soluble B which is necessary
for the maintenance of growth and health in animals.
There seems to be no vaHd reason why, if it is neces-
sary for culinary purposes, to use soda in the cook-
ing of a few foods, the practice should be discontinued.
If the diet is so planned as to furnish a suitable quota
of milk, and of cereals and other foods which are not
so treated as to destroy the water-soluble B there is
no danger of a shortage of this substance in the diet.
It is now well demonstrated that with the diets employed
in Europe and America there is no such thing as a
^^vitamine" problem other than that of securing an
adequate amount of the substance fat-soluble A. Seeds
and their products, tubers, roots and meats in the
amount in which they are ordinarily consmned, do
not fmnish enough of this substance for the mainte-
nance of an optimmn state of well-being. Diets com-
posed of these substances exclusively, may, when
their other deficiencies are corrected, contain enough
of the fat-soluble A to induce fairly good growth to

THE PLANNING OF THE DIET 139

nearly the full adult size, and may long prevent the
development of xerophthalmia. They do not supply
enough of it to support maximum vigor over a long
period, and fall short of the amount necessary under
the special conditions involved in pregnancy and
lactation.

There is a wide-spread belief that wheat is superior
to the other cereals as a food. There is no experi-
mental evidence that this is true. Rye, barley, oats
and maize resemble wheat very closely in their diet-
ary properties, and it is safe to say that these can
entirely replace wheat in the diet of children, adults
and invalids without the least detriment to health.
Those who have become accustomed to the use of
wheat bread, are attached to it principally because
of habit. Dietary habits become very firmly fixed
and are hard to break away from. Millions in the
Orient are greatly attached to rice as a food, and
feel that they cannot live without it, whereas, we in
America cannot bring ourselves to eat Uberally of it
in the simple and unappetizing form in which it is
entirety acceptable in the Oriental. The Italian
feels that no diet is satisfactory unless it contains
macaroni. GarUc and other flavors which appeal to
the appetite of certain peoples are disliked by others.
These prejudices and many others are not expressions
of physiological need, but are purely demands for
something to which we have become accustomed.
When properly cooked, commeal, oats and other
cereals have never been shown to produce digestive

140 THE NEWER KNOWLEDGE OF NUTRITION

disturbances. Reports that the people of Belgium,
when restricted to the scanty fare which could be
furnished them after the occupation of their territory
by Germany, suffered from digestive disturbances
from eating com bread, are not to be taken as evi-
dence that the corn products were in themselves re-
sponsible for the trouble. They were the sequel of
an inadequate diet which impaired the vitality.
Experiments have been described, showing that
bolted wheat flour is inferior to whole wheat. ^ If
two pigeons are fed whole wheat and bolted flour re-
spectively, while a third is allowed to fast, the first
will remain in a state of apparent health for several
weeks, the second will lose weight and die earher than
the fasting one. This does not mean that bolted flour
is poisonous, but only that it is a more incomplete
food than whole wheat. The pigeon which is fed
whole wheat will succimib in the course of time, for
whole wheat is not a complete food. The pigeon
which fasts gradually wastes away, but slowly, be-
cause all the tissues decrease in volinne and its physi-
ological processes slow down. The bird which is fed
the bolted flour dies earher than the fasted one, be-
cause the burden of digesting and metaboUzing a
liberal intake of food requires that his metaboUc
processes go on at a rapid rate. When this demand
is made upon it and its diet is so incomplete that
there can be no repair of its wasted tissues, it wears
out the more quickly. Such demonstrations do not
constitute an argument agaiast the use of wheat flour ^

THE PLANNING OF THE DIET 141

as a food. In so far as the latter supplies protein,
energy and inorganic salts, it is a good food. What
we should reaUze is that none of our vegetable foods
or the meats are complete and ideal foods. Some are
more deficient than others, and their deficiencies are
not all alike. Satisfactory nutrition is to be attained
only through the employment of the right combi-
nations of foods, and in such proportions as will in-
sure that the resulting diet will be properly con-
stituted. We should accept our natural foods for
what they are, and make proper use of them, rather
than condemn this or that one because it is lacking
in some respect.

It is fallacious reasoning to attempt to compare
the money value of certain foods with certain others.
We may safely compare the cost of the cereal grains
or the legumes with each other, or with the tubers
such as the potato or the sweet potato, or with the
root foods. It is not possible to compare the cost of
any of these with milk or the leafy vegetables such
as cabbage, cauliflower, Swiss chard, coUards,
Brussel sprouts, onions, lettuce, celery tops, spinach,
turnip tops and other leaves employed as greens.
Milk and the leafy vegetables are to be regarded as
protective foods. In some degree eggs are to be con-
sidered in the same class. Milk and the leafy vege-
tables should be taken in Uberal amounts. The
leaves should not be regarded as foods of low value
because their content of protein, fat and carbohy-
drate is low, and the content of water high. When

142 THE NEWER KNOWLEDGE OF NUTRITION

compared on the basis of chemical composition they
appear inferior to seeds, but they have a pecuUar
value in their high content of fat-soluble A and of
mineral elements, which makes them stand m a
class by themselves among the vegetable food-stufifs.

No thorough studies of the dietary properties of
fruits have yet been made, but from their known
chemical composition and biological functions as
storage organs, their proper place in the diet can be
predicted. They are good sources of mineral salts
and of energy-yielding foods, the sugars. They are
highly palatable and exert a favorable influence on
the excretory processes of the kidneys and the in-
testine. Their liberal use in the diet should be en-
couraged.

Owing to the present shortage of certain food-
stuffs, there has been a tendency to consider the in-
troduction of certain new products hitherto not
generally employed in a large way as human foods,
and to extend their use by extolling their virtues.
Conspicuous among these are the peanut press cake,
which remains after the oil is extracted by pressure,
the soy bean and cottonseed flour. The latter prod-
uct represents a portion of the cottonseed which is
prepared by first removing the oil, and afterward
grinding and bolting to obtain a product free from
hulls and fiber. These movements directed toward
the utilization of all our food resources are laudable,
but the information which is disseminated con-
cerning these products by their enthusiastic pro-

THE PLANNING OF THE DIET 143

moters is not in all cases accurate and sufficiently
corr plete to serve as a safe guide to the user. They
are extolled in the time-honored fashion as foods
rich in protein and energy, but their exact place in
the dietary is not sufficiently emphasized.

There can be no doubt that the peanut is a whole-
some food, and can be used to advantage in the diet
of man in moderate amounts. It is likewise a good
source of protein of fairly good quality. The same
can be said of the soy bean. The proteins of neither
of these have extraordinary values. That there are
no proteins of extraordinary values in the seeds of
plants yet studied, is apparent from a critical and
unprejudiced inspection of all of the extensive ex-
perimental data available. The point to be em-
phasized in this connection, is that these are seed jyrodr
tecte, and have in a general way the peculiar dietary
properties common to seeds. Their place in the diet
is therefore clear. They may be employed in m oder-
ate amounts along with other seeds and seed prod-
ucts, provided that they are supplemented with
sufficient amounts of the protective foods, milk and
the leafy vegetables.

With respect to cottonseed products the case is
somewhat different. The cottonseed has long been
known to contain something toxic to animals, and ex-
perience has taught that cottonseed meal, a product
containing the hulls, cannot be fed Uberally to animals
without disastrous results. Withers and Carruth^
have conducted extensive investigations regarding

144 THE NEWER KNOWLEDGE OF NUTRITION

the nature of the toxic constituent, and have iso-
lated it as a substance to which the name gossypol
has been given. It is destroyed by oxidation, and
by appropriate heat treatment, and some cotton-
seed products are much less poisonous than others,
because of the special treatment which they have
received. The author has fed cottonseed flour to a
large nmnber of animals, and is convinced that it
should not be employed in the human dietary in very
liberal amounts. If the diet is appropriately con-
stituted with respect to its content of the protective
foods, cottonseed flour which has been thoroughly
cooked, will, when used in moderation, be found to be
a useful food-stuff. The data available emphasize the
need for further careful studies to show how much
heat treatment is necessary to render cottonseed
flour harmless. Such knowledge, when available, ^
will make possible the standardization of commercial
products, and will make possible the utilization of
this vast food resource.

The paramount importance of maintaining and
of increasing the production of milk makes it neces-
sary to utilize a large amount of protein-rich foods in
the dairy industry. The wisest plan is to extend the
use of peanut, soy bean and cottonseed products for
milk production. The cow produces much of her
milk from coarse feeds, not suitable for human con-
sumption, but requires Uberal protein-rich supple-
ments in addition. Greater emphasis should be laid
upon the wisdom of a more liberal purchase of milk

THE PLANNING OF THE DIET 145

by the public. This would insure the best utiliza-
tion of these protein-rich products which have not
as yet in many quarters found extensive use as hu-
man foods. Experimental data seems to have es-
tablished that the proteins of the peanut and the soy
bean are of better quaUty than those of the pea or
the navy bean. From the author's studies of the soy
bean it appears that its proteins have about the
same quaUty as those of the cereal grains, but it con-
tains three times as much protein as the latter. Its
content of fat-soluble A is such that a mixture of
soy bean and starch which has the same proteia con-
tent as the wheat kernel, probably has about the
same dietary properties as has wheat with respect to
these two dietary factors. There is no reason why
the peanut and soy bean should not be employed to
a greater extent as hiunan foods, but it should be
kept in mind that good use is already beiag made of
these products in the feeding of dairy cows, and that
if they are withdrawn from this application for use
as human foods directly, it will not be easy to find
something to take their place in the dairy industry.
Several writers have pointed out that these seeds
contain the fat-soluble A, atid have exhibited growth
curves which indicate that animals have taken one of
these seeds properly supplemented so as to correct
its deficiencies, and have been able to grow to ap-
proximately the full adult size without the addition
of more of this dietary essential. The reader is left
with the impression that the peanut, soy bean and

146 THE NEWER KNOWLEDGE OF NUTRITION

cottonseed may serve as an adequate source of fat-
soluble A. This impression is an imfortunate one,
for it is certain that even with diets which are com-
posed largely of these seeds, the content of this sub-
staQce is below the optimum, and m the amounts in
which they are likely to enter into the human diet,
they win never serve as a substitute for the pro-
tective foods. In the enthusiastic application of the
biological method for the analysis of food-stuffs, by
those with little experience, after its description by
McCollum and Davis in 1915,^ hasty conclusions
have been drawn in a number 'of instances, Mc-
Collum and Simmonds have emphasized the necessity
of observing over long periods, such animals as are
able to grow at about the normal rate and produce
a few young and rear them, when confined to ex-
perimental diets. In many instances it is foimd that
the interval between litters is too long, or the mor-
tality of the young abnormally high, the time neces-
sary to bring the young to the weaning stage too
long and the signs of old age appear too early, in
animals which during the early part of the reproduc-
tive period appeared to be nearly normal in all re-
spects. They have reached the conclusion that it is
necessary to observe the behavior of the second
generation when confined to the diet of the parent
before drawing final conclusions concerning the
quality of a diet. In many instances lack of vitality
is first observed in the inability of the offspring to
develop normally on a diet which would, in the early

THE PLANNING OF THE DIET 147

life of the parent, have been considered entirely sat-
isfactory. When observations are extended in this
way, it becomes apparent that lung infections very
frequently terminate the lives of the animals, whose
diets are faulty in some degree, but not so faulty as to
make their effects strikingly apparent.

From many questions asked by the pubUc the au-
thor has gained the conviction that faulty deductions
have been drawn by others from experimental
studies, which would lead the inexperienced reader
to conclude that by the use of any seed products, or
other food-stufifs of vegetable origin, whose func-
tions are those of storage organs, that diets can be
prepared which are so satisfactory as to make it
feasible to dispense with a hberal intake of the f ood-
stuflfs which we have designated as protective foods.
These can be shown to be based upon failure to fully
appreciate what constitutes a satisfactory demon-
stration of the adequacy of a diet. Mankind will do
well to avoid such diets which may, as Golderger
has suggested, place one in ''a 'twilight' zone within
which a very sUght change in any of the dietary
components may cause an important shift of bal-
ance.''

McCoUum and Sinunonds have reported many
experiments with diets so planned as to be satisfac-
tory in that all the factors but one afforded a liberal
margin of safety in offering an abundance over the
xrinimatl requirements of the animal,^ and the re-
maining one so adjusted as to represent the actual

148 THE NEWER KNOWLEDGE OF NUTRITION

minimum on which the animal can subsist over a
considerable period. In this way it has been possible
to demonstrate that the amount of fat-soluble A
may be reduced to a certain minimum without the
development of xerophthalmia, whereas the same
intake of this substance will not prevent the charac-
teristic eye trouble when the intake of protein is
likewise sufficiently lowered. They have been able
to so adjust the components of the diet as to make
it possible to relieve xerophthalmia either by in-
creasmg the content of protein or of fat-soluble A
iQ the food, although it is the lack of the latter which
is the specific cause of the disease. Such observations
make it evident that it is impossible to say what is
the safe minimum of any dietary factor, imless the
biological values of all the other essential constituents
of the diet are known. This represents an actual
accomplishment of planning a diet which brings
the animal into the 'Hwilight" zone, where small
shifts in the quality of the diet with respect to any
factor may either distinctly stabilize the metaboUc
processes of the animal, or may lead to the develop-
ment of a distinct pathologic state.

Their studies with the types of diets just described,
lead them to the conclusion that it is unwise to
approach very closely the physiological minimum
with respect to any dietary factor. Liberal consump-
Hon of all of the essential constituents of a normal diet,
prompt digestion and absorption and prompt evacuation
of the undigested residue from the intestine before exr

THE PLANNING OF THE DIET 149

tensive absorption of products of bacterial decomposition
of proteins can take place, are the optimum conditions
for the maintenance of vigor and the characteristics
of youth. Such a dietary r^giine can be attained only
by supplementing the seed products, tubers, roots
and meat, which must constitute the bulk of the
diet of man, with the protective foods, milk and the
leafy vegetables.

The results of the study of several representatives
of each of the different classes of food-stuffs has led
the author to the conclusion that, while it is not de-
sirable to relegate to the backgroimd any of the
fimdamental knowledge of food-stuffs which can be
obtamed by chemical methods, and by respiration
and digestion studies, the fundamental basis of nutri-
tion can best be imparted to the pubUc through the
adoption of a biological classification of the natural
food-stuffs on the basis of their function. Foods
other than milk and eggs of both animal and veg-
etable origin may be arranged into groups according
to whether they represent principally, functioning
active protoplasm, or deposits of reserve food mate-
rial, or in animal tissues, highly specialized contract-
ile tissues. From their biological fimction their
dietary properties can be fairly accurately predicted.
This idea, together with the knowledge that n^iilk,
eggs and the leafy vegetables, the Trrotec tive foods,
are s o constituted as to correct the dietary Hftfinian fiifts
of the seeds^ tubers. ^oots an d meat, should fo rm
the central idea in the teaching of the science,Df

150 THE NEWER KNOWLEDGE OF NUTRITION

nutritio n. It should be emphasized that the diet is
a relatively complex thing, and that none of the
essential constituents can be ignored m its planning,
but that the observance of certain general rules of
procedure will insure that any faults in the diet
will be reduced to a minimum. "^

It is of special moment at this time to emphasize
the importance of the dair y industry in its relation
to the p ublic hea lth. Mankind may be roughly
classified into two groups. Both of these have d^
rived the greater part of their food supply from
seeds, tubers, roots and meat, but have differed in
respect to the character of the remainder of their
diets. One group, represented by the Chinese,
Japanese and the peoples of the Tropics generally,
have employed the leaves of plants as almost their
sole protective food. They likewise eat eggs and
these serve to correct their diet. The other group
includes the peoples of Exurope and North America
and a few others. These have likewise made use
of the leaves of plants, but in lesser degree, and have,
in addition, derived a very considerable part of their
food supply from milk and its products.

Those peoples-^w^iQ-have^mployed t he leaf i of the
plRTit^fl^gJJTPir Rolft protective food are cha racterised
by s mall sta ture, rftla-tivftly shori; Rpfl.T\ of lifp, high
inf ant mortalit y, and b y contended adherence jkL^
empl oyment^ of the simn le mech anical inven tions of
their forefathe rs. The peoples who have made Ub-
eral use of milk as a food, have, in contrast, attamfed

THE PLANNING OF THE DIET 151

greater RJ7g^_gTA5i.t.Ar l|>7ip;ftvity, and have been muc h
more s uccessful m the rearing of their voim g. They
have been mo re aggressive than the non-milk Ji sins
peo ples^ and have achieved much greater advanc ft-
men t in literature, science and^ axt. They have
devel oped in a hig h er degre e educ^ onal and j>Qlit-
ical syst ^as which offer the greatest, nppnrti^yiity
for the mdividual to devel op his pow ers. Such
development Has a physiological basis, and there
feeems every reason to beUeve that it is fundamentally
related to nutrition.

In the United States, we have in the past de-
rived no less than 15 to 20 per cent of our total
food supply from the products of the dairy. The
investigations of recent years have thrown a new
light on the importance of this increment of our diet.
It has become evident that milk is the greatest
factor of safety in our nutrition, and it is certain
that we could not have accomplished what we have,
had we dispensed with milk as a food.

The situation of the daiiy industry is at the present
time precarious. The cost of feeding-stuffs and of
labor have enormously increased during the last
few years, and consequently the cost of milk produc-
tion. Advance in the cost of milk to the consumer
has been made unavoidable. Every advance in the
price has, however, met with great resistance by the
public, and with each rise there has been a distinct
drop in the amount purchased. The milk deUvered
in the city of Chicago has fallen off from about a

152 THE NEWER KNOWLEDGE OF NUTRITION

million and a quarter quarts daily to about seven
hundred thousand quarts, within a year. Similar
reductions in sales have occurred ahnost eveiywhere
in the Eastern half of the country, solely because of
the rise in price. This has resulted in the discourage-
ment of producers everywhere, and in a movement
toward the reduction of the number of dairy cows.

There can be no doubt that there is great lack of
knowledge by the people generally as to the impor-
tance of milk and other dairy products in the diet.
There is no substitute for milk, and its use should
be distinctly increased instead of diminished, re-
gardless of cost. Every possible means should be
employed to reduce the cost of distribution. The
necessity for the liberal use of milk and its products
both in the diets of children and adults should be
emphasized in order to stem the ebbing tide of its
production. It has been pointed out that the value
of milk as a food cannot be estimated on the basis
of its content of protein and energy. Even when
measured by this standard it compares most favor-
ably with other foods, but it has a value as a protect-
ive food, in improving the quaUty of the diet, which
can be estimated only in terms of health and effi-
ciency.

An examination of any large groups of people in
the cities, will show that where there is a high mor-
taUty from tuberculosis, milk is not being used to
any great extent, and in any large group where
milk piu'chases are large this disease is not a menace.

THE PLANNING OF THE DIET 153

It is well known that in institutions where tuber-
culosis is successfully treated milk forms the prin-
cipal article of the diet of the inmates. This has
resulted from clinical experience. There is no other
effective treatment for this disease than that of
providing fresh air, insisting upon rest and of height-
ening the body's powers of resistance through the
liberal use of milk for the correction of faults which
the diet will inevitably have when it consists too
largely of seed products, tubers, roots and meats.
The importance of diets of this character in the
etiology of tuberculosis, has not hitherto been
appreciated. In the Ught of facts presented in the
previous chapters of this book, there can be no
reasonable doubt that the importance of poor
hygienic conditions and of poor ventilation have
been greatly over-estimated, and that of poor diet
not at all adequately appreciated as factors in pro-
moting the spread of this disease. Milk is just as
necessary iq the diet of the adult as ia that of the
growing child. Any diet which will not support
normal development ia the yoimg will not support
optimmn well-being ia the adult. Milk is our greatest
protective food, and its use must be increased. The
price must be allowed to go up, so long as the cost
of production makes it necessary, and up so far as is
essential to make milk production a profitable busi-
ness. Unless this is done, the effects will soon be-
come apparent in a loweriag of om- standards of
health and efficiency.

INTRODUCTION TO THE LEGENDS TO THE

CHARTS

The data upon which the foregomg discussion of
diet is based, consists of about three thousand feeding
experiments. Most of these were carried out with
domestic rats, but in order to demonstrate the gen-
eral appUcability of the results of tests made on one
species to other species of animals, niunerous feeding
tests were made on farm pigs, cattle, chickens,
guinea pigs and a few on pigeons. These all indicate
that the chemical requirements of these different
types of animals are essentially the same. The
following charts present the growth curves of rats,
fed a series of diets which illustrate the type of re-
sults from which the conclusions in this book are
drawn. In each case the curve is the actual record
of an individual which fairly represents the behavior
of from fom" to six or more animals.

The broken curve marked N with the sex sign
(cf = male; 9 = female) represents the normal ex-
pectation of growth in each sex when fed a mixed
diet containing several seeds and a liberal supply
of milk. Vertically the curves designate body weight ;
horizontally from left to right the charts record
diu*ation of experiment, each square representing

154

LEGENDS TO THE CHARTS 155

four weeks. A break in a curve marked Y, indicates
the birth of a Utter of young.

Although experiments are described only for the
wheat, rice atid oat kernel among the seeds, similar
records are available for all the more important
seeds used as foods in America, and these warrant
the statement that seeds as a class closely resemble
each other in their dietary properties. A close re-
semblance likewise exists among the several leaves
which have been studied, so that the edible leaves
may be regarded as having in a general way the same
dietaxy properties.

Chart 1. — ^Lot 417 shows the results of restricting young rats to
a diet of purified protein, salts, carbohydrate and agar-agar, together
with an extract of a natural food-stuff which furnishes the dietary
factor, water-soluble B, the substance which prevents beri-beri.
The diet was complete except for the absence of the fat-soluble A.
As a rule there develops in animals so fed, a t3q>e of xerophthalmia,
which is due to the lack of the fat-soluble A. When a fat or other
natural food which is rich in cellular structures (as contrasted \yith
reserve food materials), is added to a food mixture of this t3q>e, the
resulting diet becomes capable of inducing growth.

Lot 418, Period 1, shows the curves of body weight of rats fed a diet
similar to that described above for Lot 417, but differing in that it
contained butter fat (fat-soluble A) but lacked the extract of natural
foods, and, therefore, contained no water-soluble B. On this diet
xerophthalmia does not develop, but the animals ultimately lose
muscular control and manifest symptoms suggestive of beri-beri in
man. Growth is not possible on this diet, but everything which is
needed in the diet so far as chemical analysis could show, is present.

These results show the necessity of a biological analysis of food-
stuffs. Growth at once took place when, in Period 2, the dietary
essential water-soluble B, which is likewise soluble in alcohol, was
added to the diet. This dietary factor is abundant in all natural

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LEGENDS TO THE CHARTS 157

foods. In investigations of the nature of those here described, it is
usually added as an alcoholic extract of a natural food.

Lot 419 shows the type of growth curves secured with diets con-
taining both fat-soluble A and water-soluble B, in addition to the
long recognized food substances, protein, carbohydrate, fat and a
satisfactory supply of the inorganic elements essential for the nutri-
tion of an animal. There is much reason to beUeve that each of the
two unidentified dietary factors A and B contains but a single chem-
ical complex which is physiologically indispensable, and not a group
of such substances.

Chart 2. — ^This chart illustrates the nature of the dietary defi-
ciences of the cereal grains, as revealed by feeding a single variety
of seed with the addition of certain piu'ified food substances. Wheat
is a typical representative of the group of seeds.

The wheat kernel when fed as the sole source of nutriment, or when
supplemented with protein alone or with fat-soluble A alone (in
butter fat), does not induce any growth in a young animal. Wheat
supplemented with the three inorganic elements, calcium, sodium
and chlorine, and with no other additions, induces slow growth for
a time. In other words, the salt content is the first limiting factor
in seeds from the dietary standpoint. These facts are not illustrated
by growth curves. ^

Lot 223 illustrates the growth of young rats when fed wheat to-
gether with two purified food additions, viz., protein and a salt
mixture of suitable composition. The dextrinized starch in this diet
has no special significance. On this diet animals may grow to nearly
the full adult size at the normal rate, and in some cases a small litter
of young may be produced. The young as a rule will be allowed to
die within a few tiays. On such a diet xerophthalmia will ultimately
develop, and this forms the terminal event in the Uves of the animals.
This shows that the content of fat-soluble A in wheat is below the
amount required to maintain an animal in a state of health over a
long period. This fact is further illustrated by the record of rat
223-B, whose diet was Uke that of 223, except that the former con-
tained 5 per cent of butter fat. Butter fat is the best known soiu'ce
of fat-soluble A.

Lot 380, Period 1, shows how slowly growth proceeds when the
diet consists of wheat, supplemented with two purified food addi-
tions, protein and fat-soluble A (as butter fat). The deficiency of

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LEGENDS TO THE CHARTS 159

the wheat kernel in certain inorganic elements is illustrated by the
great acceleration of growth in Period 2, when a suitably constituted
salt mixture was added to the diet of Period 1.

Lot 319 shows the slow growth of a rat when fed wheat supple-
mented only with the requisite inorganic salts and fat-soluble A.
The proteins of the wheat kernel are not of very good quality, and
must be enhanced by further protein additions before growth can be
normal.

Lot 223-B illustrates the fact that the optimum rate of growth is
secured with wheat supplemented with three purified food addi-
tions, viz., salts, fat-soluble A and protein. When wheat is improved
■with respect to these three dietary factors, it becomes a complete
food, and supports the production of the normal nimiber of young,
and the young are successfully reared. What is true of wheat is
likewise true in a general way of the other seeds. Seeds are similar
in their dietary properties. In other words, the mineral content of
any seed must be improved by suitable salt additions, its protein
content must be enhanced by the addition of other proteins which
yield in greater abundance those amino-acids which it pelds in small
amounts, and in most cases additional fat-soluble A must be added
in order to prevent the ultimate development* of a pathological con-
dition of the eyes. A Uberal supply of milk will correct all the defi-
ciencies of a seed diet.

Chart 3. — Li the process of polishing, both the germ and the bran
layer of the rice kernel are rubbed off, thus removing the cellular
structures and leaving only the endosperm. This consists almost
entirely of proteins, starch, a small amount of fats, and of mineral
elements in the form of salts. Its proteins are of relatively low value
for inducing growth. Polished rice is, therefore, practically com-
parable, from the dietary standpoint, to the diet of purified food-
stuffs described in Chart 1.

Lot 317 shows the behavior of young rats which were fed polished
rice supplemented with two dietary factors, viz., a suitable salt
mixture and fatnsoluble A. This does not support growth, since the
diet is still deficient in two respects. It lacks the second dietary
essential, waternsoluble B, and its proteins are of too poor quality
for the support of growth in the amount supplied by 90 per cent of
rice. Such a diet as that of Lot 317 wiU permit the development
of a condition in rats similar to beri-beri in man.

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LEGENDS TO THE CHARTS 161

Lot 324 shows the effects on young rats of feeding them on a
mixture consisting of polished rice supplemented with purified pro-
tein, a suitable salt mixture and fat-soluble A. The polished rice
evidently contains some cellular elements anH, therefore, some of the
water-soluble B, for the animals were able to grow very slowly in
some cases, and to remain alive during several months. Lot 401
illustrates the remarkable effects of adding to this diet an alcoholic
extract of wheat germ. This extract furnished a Uberal amount of
water-soluble B (likewise soluble in alcohol) and renders the diet
complete. The alcohol was employed to dissolve this dietary essen-
tial from the germ, and was evaporated completely before the ration
was fed.

Lot 383 shows the dietary properties of unpolished as contrasted
with polished rice. The former which contains the ceUular struc-
tures of the germ and the bran layer, is rendered complete as a food
by the addition of protein, fat-soluble A and salts. Young rats do
not grow at all when fed solely upon unpolished rice, without these
additions. Unpolished rice closely resembles wheat, corn, rye,
barley and other seeds in its dietary properties.

Lot 401 shows the behavior of young animals when fed polished
rice supplemented in four respects, viz., protein, a suitable salt
mixture, fat-soluble A and water-soluble B. On this diet, young rats
grew to the normal adult size, reproduced repeatedly and were able
to rear a few of their young. The omission of any one of these addi-
tions would lead to almost complete failure of young animals to
develop on this diet.

These examples make clear the method of procedure in making a
biological analysis of a food-stuff. The latter consists of a suitably
planned series of feeding experiments in which single and multiple
purified food additions are made to a single natural food-stuff, and
observations are made as to the ability of young animals to grow
and perform the functions of adult life on the resulting food mixtures.
In this way information can be secured which chemical methods
are unable to reveal.

Chart 4. — ^These records illustrate the biological analysis of the
dietary properties of the oat kernel (rolled oats). Lots 623 and 654
show the failure of young rats to grow on rolled oats supplemented
with either a suitable inorganic mixture, or with purified protein
as the only addition. Correction of these factors is necessary, but

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there are still other faults in the oat kernel which must be corrected
before it becomes a complete food. This is illustrated by the re-
maining records in this chart.

Lot 625 shows that when the oat kernel is supplemented with
both a suitable salt mixture and fat-soluble A, it can support growth
at a good rate for three months, but does not permit the animal to
reach full adult size, and leads to early failure. The protein of the
oat kernel has a slightly higher value for growth than has that of
either wheat or com, but the amount fmnished by 90 per cent of
rolled oats is below the optimum for the support of growth in a
rapidly growing species. A diet rich in rolled oats produces very
hard, pasty feces, which are difficult of elimination. This appears
to be a factor of importance in preventing the normal development
of the experimental animals in this series.

Lot 624 further illustrates the inadequacy of rolled oats sup-
plemented with both a suitable salt mixture and protein (casein).
This food mixture lacks a sufficient amount of fat-soluble A, and
unless there is an addition of this substance, the animals always
develop the eye trouble (xerophthalmia) described on page 87.

Lot 655, shows the growth curve of an animal fed rolled oats
supplemented with protein, an appropriate mineral salt mixture and
fat-soluble A. In this case the protein employed was casein of milk.
This ration is dietetically complete, so far as its chemical composition
is involved, but it did not support normal development to the full
adult size. It is not possible to state just how far the stunting was
due to the pasty character of the feces formed from this diet, and
how far the results should be attributed to the failure of casein to
supplement the amino-acid deficiencies of the oat proteins. Much
better nutrition is secured with this diet when the casein is replaced
by another protein, gelatin, as is shown by the records of Lot 647.

Lot 647 illustrates the completeness of a diet derived from rolled
oats supplemented with an appropriate salt mixture, fat-soluble A
and the protein, gelatin. When Charts 2, 3 and 4 are compared,
they show the striking similarity from the dietary standpoint of the
three seeds, wheat, rice (unpolished) and oat kernels.

It is not to be concluded from these experiments which show the
faulty character of these seeds as foods, that they are undesirable
constituents of the diet. Neither is it necessary or practicable to
supplement in practice the seeds which we eat with additions of

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protein, salts, etc., in the manner employed in the biological analysis
of these which we have described. There are two classes of jyrotective
foods, milk and the leafy vegetables, which when taken along with
the seeds and their products, make good their deficiencies, and render
the diet complete. These correct the inorganic deficiencies {calcium,
sodium and chlorine) ^ insure a sufficient amount of fat-soluble A, and
enhance the value of the proteins of the seed.

Chabt 5. — ^Each of the more important seeds which are employed
in human and animal nutrition, have been studied by the methods
employed for wheat, rice and the oat kernel, and the results show
that the seeds all resemble each other in a general way in their dietary
properties. They all require the same kinds of supplementary addi-
tions to make them complete foods. It would be expected, therefore,
that mixtures of any seeds should not form complete diets. The
following experiments demonstrate that this is indeed the case.

Lot 722 shows the failure of animals to grow when confined to a
mixture of corn and flaxseed oil meal. After nearly four months of
stunting there was an immediate response with growth when the
inorganic content of the diet was supplemented with a suitable salt
mixture.

Mixtures of seeds will, in nearly all cases, furnish proteins in
greater value than those of the individual seeds fed singly, since the
amino-acids in which they are relatively deficient are not the same
in different seeds. The seeds all contain some of the fat-soluble A,
but not as much as is desirable in the diet. In seed mixtures there
is only a relative shortage of this dietary essential. The deficiency
of certain inorganic elements is, therefore, the first limiting factor
in mixtures of seeds as food-stuffs. In many of the growth curves
exhibited in the charts, complex salt mixtures were added, since at
the time the experiments were carried out, our knowledge concerning
the inorganic factor was still very incomplete. It is now known that
but three elements need be added to seed mixtures, viz., calcium,
sodium and chlorine.

Lot 713 shows the failure of five seeds to support growth. In
Period 2, the correction of the inorganic deficiencies of the diet was
followed by a prompt response with growth. The poor quaUty of the
proteins and relative shortage of fat-soluble A, will in time lower the
vitality of animals fed such a seed mixture, when only the inorganic
factor is corrected.

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Lot 959 shows that the addition of fatnsoluble A (as butter fat)
to a mixture of three seeds, wheat, com and oats, does not produce
a food which can support growth except at a very slow rate. In
Period 2, the correction of the inorganic deficiencies of the diet was
followed by a prompt response with growth.

Lot 1012, in Period 1, received three seeds supplemented with
both protein (casein) and fat-soluble A, but could not grow on this
diet. In Period 2, the addition of the necessary salts produced an
immediate response with growth.

Lot 714-B, which were fed three seeds, suffered complete suspen-
sion of growth. There was no response in Period 2, to the addition
of fat-soluble A in butter fat. Although both protein and fat-
soluble A are desirable additions to any seed diet, and are necessary
before the optimum nutrition can be attained, the inorganic defi-
ciencies must be corrected before any noticeable benefit can be de-
rived from the correction of the other factors. (Compare 959-714-B.)

Chabt 6. — ^In marked contrast to the failure of young animals to
grow on a diet restricted to seeds, one can secure very satisfactory
rations from mixtures of leaf and seed. The leaf is a cell rich struo-
tiu^; the seed, a cell poor storage organ. With this difference in
function go corresponding differences in dietary properties. (See
pages 43-44.)

These curves illustrate the relative values for the support of growth
and reproduction of diets derived from alfalfa leaf flour 40 per cent,
and a seed 60 per cent. It wUl be seen that these corresponding leaf
and seed mixtures are not of equal value. In a general way the leaves
all resemble each other in their dietary properties, and form a dis-
tinct group of food-stuffs as do the seeds.

Lot 685 shows the possibility of securing a normal growth curve
and repeated reproduction with a rat restricted to a mixture of alfalfa
leaf floiu* 40 per cent and rolled oats 60 per cent. Of the six litters
(33 young) borne by mothers which had grown up on this diet, 16
young or 50 per cent were successfully reared to weaning time.
Despite the fact that an animal can grow at a rate which we may
regard as normal on this food mixture, it is not of a highly satisfactory
character. Rolled oats and alfalfa leaf make a better diet than the
alfalfa leaf with any other seed which we have studied. It is inter-
esting that these proportions between alfalfa leaf and rolled oats give
better results in the nutrition of the rat than any others.

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Lots 687 and 686, show that there is little difference in the values
of mixtures of the alfalfa leaf with the wheat kernel as compared
with the corn kernel. Both, in the proportions here employed, fail
to induce growth at the "normal" rate, and the number of yoimg
produced was approximately one-fifth that which a female rat will
produce when her diet is of excellent quality. A well-nourished
female rat may be expected to produce five Utters of young.

Lot 478 shows that even with a simple mixture of alfalfa leaf
flour 40 per cent and polished rice 60 per cent, rats were able to grow
to about 83 per cent of the normal adult size and to produce young.
The rat whose curve is shown had two Utters. All young from
mothers which had grown up on this diet were aUowed to die during
the first few days after birth.

Lots 688 and 717, show that combinations of peas or of cottonseed
with the aKalfa leaf flour form food mixtures which can support
growth at a slow rate, but are inferior to certain other combinations
of leaf and seed.

There are very great possibiUties for improving our practices in
the utilization of feeding-stuffs in animal production. We need
exact knowledge regarding the best combinations and proportions
in which to feed our natural products.

Chart 7. — It is easily possible to prepare diets which are derived
solely from vegetable sources, which wiU induce growth from weaning
time to full adult size and support the production of young. Success
in this direction involves the emplojrment of suitable combinations
of leaves, together with foods of plant origin whose fimctions are
those of storage organs, viz.: seeds, tubers, and roots. The records
here presented show the most successful results which we have ob-
tained with mixtures of leaf and seeds.

Lot 273 shows the results of restricting young rats from weaning
time to a diet derived entirely from the alfalfa leaf flour, com and
peas. The peas were cooked at 15 pounds pressure for one hour in an
autoclave. The other constituents of the diet were fed raw.

The female rat marked. First Generation, never grew to the full
adult size, but others in the same cage with her did. The curve of
this particular rat is presented because she became the great grand-
mother of a Utter whose ascendants for four generations ate, beyond
the weaning age, nothing but this monotonous mixture of vegetable
foods.

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This ration did not induce optimum nutrition. The niunber of
young produced was approximately half what well-fed rats normally
produce, and the mortality of the young was high. Although the
breeding records were poor and the litters small, most of these young
were reared. Notwithstanding this, the vigor of the fourth genera-
tion appeared to be as great as that of the first.

The above mixtiu*e gives better results in the nutrition of the rat
than any other proportions in which these three food-stuffs can be
combined. If the amount of alfalfa leaf is raised to 40 per cent or
reduced to 20 per cent, and the content of com is reduced or increased
respectively, few young will be reared. The importance of knowing
the exact proportions in which to combine our natural food-stufifs
in order to secure the optimiun results in nutrition, especially in
animal production, wUl be evident from these results.

Chart 8. — This chart affords an illustration of the great differences
in the degree in which a supplementary addition of protein may en-
hance the value of the proteins of a natural food-stuff. The curves
should be considered in pairs.

Lot 493 shows the results of feeding a diet deriving its protein
content entirely from the wheat kernel. The diet contained but 7
per cent of protein, an amount too small because of the relatively
poor quality of the wheat proteins, to support growth at the optimum
rate. The group of rats which were fed this diet grew at about half
the normal rate.

Lot 652 received the same diet, with 10 per cent of the carbo-
hydrate replaced by the protein gelatin. The latter is one of the
''incomplete'' proteins, since it lacks three of the amino-acids which
are essential for the nutrition of an animal. A diet which contains
gelatin as its sole protein, no matter how much gelatin it may con-
tain, cannot induce any growth whatever in a young animal. Lot
652, however, grew at the optimum rate. This result shows that the
added gelatin made good a limited supply of certain amino-acids in
the wheat proteins of the diet. This formed the limiting factor in
determining the slow rate of growth in Lot 493. Gelatin is shown by
this experiment to supplement well the proteins of the wheat kernel.

Lots 756 and 785, show the stunting of young rats fed diets which
derived their protein entirely from a mixtiu*e of peas and gelatin,
and a mixture of navy beans and gelatin respectively. Both diets
contained about 18 per cent of protein. When of good quality this

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amount suflBces for the support of normal growth. Combinations
of pea proteins with gelatin, and of bean proteins with gelatin, 3rield
amino-acid mixtures which are deficient in some way.

In Period 2 in both cases, the diets differed from those of Period 1,
only in that the gelatin was replaced by an equal amount of casein
from milk. This change led to great improvement in the quality of
the protein in the diets, and growth at once proceeded at a good rate.
Gelatin does not greatly enhance the value of the proteins of either
the pea or the bean, whereas casein does.

Lots 646 and 647 show the effect on growth, of feeding a diet con-
taining but 9 per cent of protein derived solely from rolled oats
(Lot 646), and the same diet with 10 per cent of carbohydrate re-
placed by gelatin. In the former case, growth was early suspended,
but in the latter, growth proceeded at the optimum rate to full
maturity. This result shows that gelatin supplements the proteins
of the oat kernel in a very satisfactory manner. (See discussion
under Lots 493 and 652.)

Lots 649 and 651, show the growth curves of rats fed, in the former
case a diet which derived its protein content of about 7 per cent
entirely from the corn kernel, and in the latter case the same diet
with 10 per cent of its carbohydrate replaced by gelatin. In marked
contrast to the effects of feeding gelatin together with wheat or oat
proteins, there is no improvement in the quality of corn proteins
through combining these with gelatin. Gelatin does not supplement
the peculiar amino-acid deficiencies of the corn kernel.

Chart 9. — The records in this chart give an idea of the values of
the proteins derived from mixtures of two seeds. Each of the diets
described contained 9 per cent of protein. It has been established
that this content of protein in a ration, when it is derived from either
the wheat, com or rice kernel alone, does not support growth at a
rate much faster than half the normal rate. We, therefore, fed a
series of diets in which the protein content was adjusted at this level,
and derived from combinations of two seeds, in order to find the
most fortunate combinations of seeds as sources of proteins for
growth. Normal growth is secured on diets of this character, only
in those cases where the proteins of one seed enhance those of the
other seed present in the diet. We have not been able to find any
two seeds whose proteins, when fed together even approximate the
value of the proteins of milk.

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Lot 1366, derived 3 per cent of protein from millet seed and 6 per
cent from the soy bean. The deficiencies of the diet, aside from the
character of the proteins, were all made good by suitable additions
of salts and butter fat. On this diet the growth was slow, and the
animals remained undersized. On this diet three females have pro-
duced four Utters (23) yoimg of which but three individuals were
weaned, the others being allowed to die in infancy. This protein
mixture is of relatively low biological value.

Lot 1339 derived 6 per cent of protein from rolled oats and 3 per
cent from flaxseed oil meal. Two females grew up on this diet.
One remained sterile, and the other produced but one Utter of
youpg (7). These were finaUy weaned after a long period of infancy
in which their growth was very slow. They were very smaU and
runty when weaned. A protein mixture derived from these two
seeds is of relatively poor quality.

Lot 1338 derived 6 per cent of protein from the wheat kernel and
3 per cent from flaxseed oil meal. Growth was below the normal
rate, and two females have produced but three Utters (18) young.
But five of these were successfully weaned. Proteins derived from
these two seeds are of relatively low biological value. They sufficed
for the support of a fair rate of growth, but not for the additional
strain of reproduction. This mixture must have both protein and
fat-soluble A additions in order to produce the optimiun results in
nutrition.

Chabt 10. — ^Like the preceding chart, this shows the relative
biological values of the protein mixtures derived from mixtures of
two seeds. The diet was made adequate in every respect, except
the protein, which was in all cases adjusted so as to form 9 per cent
of the food mixture. The reason for this has been made clear in the
discussion of Chart 9.

Lot 1350 derived 6 per cent of protein from rye, and 3 per cent
from flaxseed oil meal. Growth feU slightly below the normal
expectation. One female and her daughter have produced five Utters
(30) young, of which but five individuals have been reared. This
diet is not quite satisfactory as is shown by the reproduction records,
and because of the poor quaUty of its proteins, and shortage of fat-
soluble A.

Lot 1375 secured 6 per cent of protein from rye and 3 per cent
from millet seed. One female which grew up on this diet has had

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two litters of young, all of which were allowed to die in infancy.
Another female remained sterile. It is evident that this combination
of proteins does not form a fortunate mixture.

Lot 1378 derived 6 per cent of protein from peas and 3 per cent
from millet seed. Growth on this diet was slower than the normal
expectation, and reproduction was below normal. Two females
produced four Utters (17) of young, of which but nine individuals
were finally weaned at an advanced age. These were very small for
their age. Combinations of pea and millet seed proteins do not
appear to have a very high biological value.

These histories selected from a long series of shnilar experiments
in our records make it clear that it is not easy to find mixtures of
two seeds whose proteins are of such a character as to supplement
each other's deficiencies, in the yields of certain amino-acids, and
produce mixtures of high biological value for growth and the promo-
tion of physiological well-being. In order to demonstrate the effects
of a limited protein content, or of proteins of poor quality in the diet,
experiments must be continued over a relatively long period of time.
Observations of man or animals on such diets may lead to faulty
deductions when the experiments are of short duration.

Chart 11. — This chart illustrates in a general way the content of
the two unidentified dietary essentials, fat-soluble A and water-
soluble B, in certain natural foods. The diet in all cases consisted
principally of purified food substances, and was adequate for the
support of growth, except that its content of fat-soluble A and
water-soluble B was derived from the small addition of natural food.
As will appear from the records in Chart 12, these additions of natural
food-stuffs, probably furnished a sufficient amount of water-soluble
B to support normal growth, so it may fairly be said that these
records afford more nearly an estimation of the content of fat-soluble
A in each of the natural foods employed.

Lot 723 shows that 20 per cent of flaxseed does not supply enough
of the fat-soluble A to support normal growth in a young rat.

Lot 716, shows that 25 per cent of millet seed supplied enough of
both the unidentified dietary essentials for the support of nearly
normal growth, and induced sufficiently good nutrition to make
possible the production of nearly the normal number of young.
The female rat usually produces five fitters of young before she
reaches the age of fourteen months, which age marks the end of her

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period of fertility. The rat whose curve is shown, had four litters
during the first thirteen months of her life. The first two litters died
early, but the third and fourth, which were bom after butter fat
(more fat-soluble A) was added to the mother's diet, were success-
fully brought to weaning age.

Lot 633, whose diet derived both the unidentified dietary essentials
from its content of 20 per cent of alfalfa leaf, remained distinctly
undersized, and produced but two Utters of young, all of which died
in early infancy.

Lot 632, which received but 10 per cent of alfalfa as its sole source
of fat-soluble A and waternsoluble B, grew slowly, and never reached
a body weight greater than half the normal adult size, and produced
no young.

Lot 631 was unable to grow at all when restricted to 5 per cent
of alfalfa leaf as its sole source of both the imidentified dietary
essentials, but responded at once with growth when the content of
leaf was raised to 30 per cent.

Lot 710 failed to grow well when restricted to a diet which derived
its fat-soluble A and water-soluble B from 15 per cent of hemp seed.
The oil seeds, judging from the limited data available, seem to con-
tain more of the fat-soluble A than do the cereal grains, but less than
millet seed. The latter is richer in this substance than any other
seed yet studied.

Chart 12. — ^These records were obtained with diets which derived
their content of water-soluble B entirely from the amount of natiu*al
food-stuff which each contained. The basal diet consisted of purified
protein, carbohydrate, a suitable mineral salt mixtiu*e, and butter
fat to furnish the fat-soluble A* The curves give an approximate
idea of the minimum amount of each of several natural food-stuffs
which are necessary to furnish sufficient water-soluble B to enable a
young rat to grow and reproduce.

Lots 645, 475 and 676 demonstrate the relative richness of the
wheat kernel in water-soluble B. Even 15 per cent furnishes enough
to enable a young rat to grow to approximately the full adult size,
and to produce several Utters of young. None can be successfully
weaned on this diet. Even with 25 per cent of wheat in the diet,
we have not seen a Utter of young brought to the weaning age when
the mother was restricted to this tjrpe of diet. When the wheat is
increased to 35 per cent of the food mixture some young can be

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reared, but the mortality is still very high. With higher levels of
wheat substituted for carbohydrate in this formula, the successful
rearing of young becomes the rule.

Lot 695 shows that 25 per cent of cooked peas in the diet as the
sole source of water-soluble B furnishes a sufficient amount of this
substance to enable young rats to grow well and produce young.
None were reared by any of the female rats in this lot. The peas
were soaked in water and heated for an hour and a quarter in an
autoclave at fifteen pounds pressure, dried and ground. This treat-
ment is approximately the equivalent of the heat employed in the
processing of canned fruits and vegetables. There seems to be Uttle
loss of water-soluble B as the result of such heating.

Lot 696 shows that 25 per cent of navy beans, which had been
soaked and heated in a manner similar to that described for peas
(Lot 695), supplied enough of water-soluble B to enable rats to grow
to full adult size and reproduce. Eight young out of eighteen young
(2 litters) were reared by mothers confined to this diet.

Chart 13. — It has been pointed out (page 46) that the tuber
and the edible root are both storage organs, and, therefore, poor in
cellular structures, and that their dietary properties are very closely
similar to the seeds. The records of young rats which were fed mix-
tures of potato and peas, supplemented in various ways according
to the biological method of food analysis, demonstrates the truth
of this assertion.

Lot 1405 illustrates the slow growth and early death of a rat fed
a mixture of peas and potato, supplemented with the mineral el-
ements, calcium, sodium and chlorine. An inspection of the remain-
ing curves in the chart reveals the fact that the diet is still deficient
with respect to fat-soluble A, and in no other respect.

Lot 1450, Period 1, shows the failure of animals to grow when fed
peas, potato and fat-soluble A. When in Period 2, pure sodium
chloride (common salt) and calcium carbonate (chalk) were added,
growth became possible at the normal rate. Two litters of young
have been born and all were successfully weaned. This result in-
dicates that the protein content derived from peas and potato is
of satisfactory character, and this conclusion is supported by the
records of Lot 1414, which has been successful in growth and repro-
duction when restricted to this protein mixture. To this mixture of
peas and potato, both the inorganic content and the content of fat-

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soluble A must be modified by suitable additions in order to make it
dietetically complete.

Lot 1423, Period 1, shows failure of animals to grow on a diet of
peas and potato supplemented with pui*ified protein. In Period 2,
fat-soluble A was added, but still growth could not take place. In
Period 3, the addition of calcium, sodium and chlorine, rendered the
diet complete. Two females have produced three litters (24) young,
of which 16 have been successfully weaned, and the remaining ones
are apparently normal, but under weaning age.

Lot 1414 shows that good growth and reproduction are possible
on a diet derived from peas and potato, supplemented with the
necessary salts and fat-soluble A, and gives an idea of the quaUty of
the protein mixture derived from these sources. It is of interest to
note that the proteins of the pea when taken in the amount furnished
by this diet (about 18 per cent) and forming the sole proteins of the
diet, do not support normal growth even when the diet is made com-
plete with respect to all other factors. The proteins of the potato
are of such a nature as to enhance the value of the proteins of the
pea.

In preparing these food materials the potatoes were steamed,
skinned, dried and ground. The peas were soaked, heated in an
autoclave at fifteen pounds pressure for an hour and a half, dried
and ground. The ingredients of the diet were ground po as to make
it impossible for the rats to pick out and eat them separately.

Chart 14. — ^These records illustrate the dietary properties of a
mixture of the com kernel and potato. Like the preceding chart
they show that this mixture closely resembles a mixture of two seeds,
and supports the view that the storage tissues of plants all resemble
each other in their dietary properties.

Lot 1^97 shows the failure of the animals to grow when fed a
mixture of corn and potato supplemented with the only inorganic
salts necessary to complete its mineral content. That no other
elements are necessary is made clear by the records of the other
animals in this chart.

Lot 1442, Period 1, shows that the addition of fat-soluble A, with-
out salts, does not make growth possible on a mixture of potato and
corn kernel. In Period 2, growth took place at once on the addition
of sodium chloride and calcium carbonate.

Lot 1415, Periods 1 and 2, illustrate the fact that the addition of

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protein (casein) alone, or of protein, and fat-soluble A, respectively,
does not make the mixture of potato and corn kernel dietetically
complete. In Period 3, when the necessary salts were added, growth
took place at once. The rat whose curve is shown has successfully
reared two litters of young (14) and her daughter, from the first
litter, has weaned a litter of seven young. The daughter has been fed
exclusively upon the diet of Period 3, since she was weaned. These
results make it clear that this mixture of com, casein, potato, butter
fat and the two salts, forms a very satisfactory diet.

Lot 1406 shows the abihty of young rats to grow and reproduce at
the Jiormal rate and rear part of their young when confined to a diet
of corn and potato supplemented with fat-soluble A and two salts,
calcium carbonate and sodium chloride. This record indicates that
the proteins derived from these two sources are of fairly good biolog-
ical value. The diet contains but 9 per cent of total crude protein
(N X 6.25). K the protein were all derived from the corn kernel, this
amoimt would not support such a good rate of growth, and no rearing
of young.

From the data available in our records, it is apparent that the
potato is a very valuable food, a conclusion which is in harmony
with the favor in which it has come to be regarded as an article of
diet for man.

Chart 15. — ^This and the following chart describe the relation of
the mother as a factor of safety in the nutrition of her young. In
nearly all of these records the mother was fed during lactation, a diet
which was faulty in some respect, and on which the young, after
the weaning age, could not grow at all. The problem was to find
to what extent the mother is able to take such faulty diets, and pro-
duce milk of a character which will support growth in her young.
The results show that the mother is capable under such dietary
limitations of providing for her offspring a better diet for growth
than she herself receives.

The mothers were fed an excellent diet until they delivered their
young. The Utter was in all cases reduced to four, in order to make
the results comparable, and in order not to place an excessive burden
upon the mother. From the day the young were born the mother
received the faulty experimental diet.

Rat 211 illustrates the rate of growth of a litter of four young
when the diet of the mother is highly satisfactory. This diet con-

186 THE NEWER KNOWLEDGE OF NUTRITION

tained a liberal amount of milk and of wheat, together with a salt
mixture and butter fat.

Rat 738 was fed nothing but rolled oats. Young after being
weaned cannot grow at all on this diet. During the first 20 days the
yoimg grew slowly, then became stunted, and died between the 40th
and 50th days. There are three types of deficiency in rolled oats:
the inorganic content is unsatisfactory, the content of fat-soluble A
is very low, and the proteins are not of very high value for growth.
Notwithstanding these deficiencies, the lactating mother was able
to produce milk having considerable growth-promoting properties.

Rat 843 was fed rolled oats with one of its deficiencies corrected,
viz : by the addition of fat-soluble A. The growth curve of her young
shows that her milk was of distinctly better quaUty than that which
she could have produced from oats alone. The young grew faster
and growth continued over a longer interval. Since the yoimg con-
tinued to grow to the 50th day, it is evident that the mother was still
supplementing the diet of oats and butter fat, which they began to
eat at about the 20th day of age, with a considerable amount of
milk which corrected the inorganic content of the oat kernel, for
without the addition of calcium, sodium and bholnne, rolled oats
cannot support growth, even when its other deficiencies are corrected.

Rat 983 did no better with her young on a diet of oats to which
both protein and fat-soluble A were added, than did rat 843, with-
out the protein addition. The first limiting factor for the mother
in milk production is the inorganic content, just as it is for growth
in the young.

Rat 899 did remarkably well in inducing growth in her young
when her diet consisted of rolled oats and a suitable addition of salts
for the correction of the inorganic deficiencies of the oat kernel.
The seed is not entirely free from fat-soluble A, and the mother seems
to have a reserve supply of this substance in her tissues which she
can, for a time, contribute to her milk.

Rat 1978, which was fed oats supplemented with salts and fat-
soluble A, induced growth at a fairly good rate in her young. The
60 per cent of oats in her diet furnished but 9 per cent of protein,
and this did. not sufiice, because of its relatively low value, for the
production of a normal milk supply. The growth of these young
after the time they became able to eat of the mother's food supply,
was much more rapid than it would have been had they not been

LEGENDS TO THE CHARTS 187

getting a supplementary milk supply from the mother during the
period covered by the growth curve.

Chart 16 contains further records of the growth of young which
were suckling mothers on diets derived from rolled oats, supple-
mented in various ways.

Chart 16. — Continuing the records described in Chart 15.

Rat 948 shows the failure of the young to develop beyond a lim-
ited degree on a diet of rolled oats supplemented with protein only.
The behavior of these young is comparable to that of Lot 738,
Chart 16. The two most serious deficiencies of the oat kernel for
milk production as for growth in the young, are the inorganic factor
and the shortage of fat-soluble A.

It was shown in Chart 8 that oat protdns combined with gelatin,
form a highly satisfactory protein mixture. This is confirmed by
the growth at half normal rate of the yoimg of rat 949, whose diet
consisted of rolled oats and gelatin. Young rats cannot grow at
all on this mixture. The mother is able to take such a faulty diet,
and furnish milk of such a character as will safeguard her young in
a most remarkable degree. Her limitations are, however, easily
apparent.

Rat 984 did slightly better in extending the lives of her young
when she was fed rolled oats plus gelatin plus butter fat (fat-soluble
A), than did rat 949, on the same food, minus the butter fat. It
should be remembered that young rats cannot grow at all, if when,
after being weaned, they are confined to this diet. The r61e of the
mother as a factor of safety in the nutrition of her yoimg is easily
seen.

Rat 1020, which was fed oats, gelatin and salts, was limited only
with respect to the relative shortage of fat-soluble A in her diet.
Nevertheless, she was able to produce milk which could induce
growth at a fairly good rate in her yoimg.

Rat 1019, was fed a diet which differed from that of 1020 only in
containing casein. This appears to have had a slightly beneficial
effect.

Rat 980 was fed rolled oats plus 20 per cent of skim milk powder.
This amount was not sufficient to correct the inorganic deficiencies
of the diet, and failed to supply enough fat-eoluble A to render the
diet satisfactory for milk production. It seems probable that the
sodium chloride content and fat-soluble A in the skim milk powder

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were the limiting factors in preventing the production of normal milk
in this case.

In answer to the question as to whether the failure of the young
to grow on the milk they received in these experiments, was not the
result of insufficiency in quantity rather than quality of milk, we
have the observations on cows, which were fed insufficient food
during lactation, and in other experiments, in which cows were
starved for common salt for periods of eight to fifteen months, and
actually died or came near death from salt starvation. Under such
conditions the milk flow was kept up over a long period in a most
surprising manner.

We have further evidence that the yoimg rats in the experiments
described, continued in some instances to grow long after they be-
came able to eat of their mother's food, when the latter was of such
a character as to permit of no growth whatever, had it not been
supplemented with a considerable amount of milk from the mother.
When it is considered that in some of these cases the young weighed
more than half as much as the mother, it must be admitted that the
milk production, even in these greatly prolonged periods of lactation,
while the mothers were taking faulty diets, must have been very
considerable.

The relation between the character of the diet of the nursing
mother and the character of the milk she produces has been dis-
cussed in Chapter 6.

BIBLIOGRAPHY

Chapter I

1. Fischer: Chemistry of the Proteins, Mann.

2. Osborne, T. B. : The Vegetable Proteins. Monographs on

Biochemistry, Longmans, Green and Company.

3. Atwater, W. A.: Bulletin 28, United States Department

of Agriculture.

4. Eijkman, C: Arch. f. Hyg., 1906, Iviii, 150.

Arch. path. Anat., 1897, cxlviii, 523,

5. Henriques and Hansen: Zeitschr. flir physiol. chem., 1905,

xliii, 417.

6. WiUcock, E. G., and Hopkins, F. G.: Jour. Physiol., 1906,

XXXV, 88.

7. Wise. Agric. Expt. Sta., Research Bull., No. 17 (1911).

8. McCollum, E. V., and Davis, M.: Jour. Biol. Chem., 1913,

XV, 167.

9. Stepp, W.: Biochem. Ztschr., 1909, xxii, 452; Ztschr. f.

Biol, 1912, Ivii, 135; Ibid, 1912-1913, lix, 366.

10. Hopkms, F. G.: Jour. Physiol, 1912, xliv, 425.

11. Funk, C: Lancet, London, 1911, ii, 1266.

12. Fraser, H., and Stanton, A. T. : Lancet, London, March 12,

1910, 733; The Etiology of Beri-Beri, Study 12, from
the Institute for Medical Research, Federated Malay
States, 1911.

13. McCollum and Davis: Jour. Biol. Chem., 1915, xxiii, 247;
McCollum, E. v., Sunmonds, N., and Pitz, W.: Ibid, 1916,

XXV, 105.

14. Funk and Macallum: Jour. Biol. Chem., 1915, xxiii, 419.

15. Henry, W. A.: Wisconsin Agric. Expt. Sta., Annual Re-

port, 1889, 15.

191

192 BIBLIOGRAPHY

16. Funk, C: J. State Med., 1912, xx, 341; Biochem. Bull.,

1915, iv, 304.

17. McCollum and Davis: Jour. Biol. Chem., 1915, xxiii, 181,

18. McCollum and Davis: Jour. Biol. Chem., 1915, xxiii, 231,

19. McCollum, E. V., and Kennedy, C: Jour. Biol. Chem.,

1916, xxiv, 491.

20. Osborne, T. B., and Mendel, L. B.: Jour. Biol. Chem.,

1913, xvi, 431.

Chapter II

1. McCollum, Sinmionds and Pitz: Jour. Biol. Chem., 1917,

xxix, 341.

2. Smith, Theobold: Bureau of Animal Industry, Bacilli in

Swine Disease, 1895-1896, 172.

3. Hoist, A., and Frolich, T.: Z. Hyg. u. Infektionskrankh,

1913, Ixxv, 334.

4. McCollum and Pitz: Jour. Biol. Chem., 1917, xxxi, 229.
6. McCollum and Simmonds: Jour. Biol. Chem., 1917, xxxii,

181.

6. McCollum and Simmonds: Jour. Biol. Chem., 1918,

xxxiii, 55.

7. Hart, E. B., McCollum, E. V., Steenbock, H., and Hum-

phery, G. C: Wise. Agric. Expt. Sta. Research Bull.,

17, 1911.
Hart and McCollum: Join*. Biol. Chem., 1914, xix, 373.
McCollum and Davis: Jour. Biol. Chem., 1915, xxi, 615.
McCollum, Simmonds and Pitz: Ibid, 1916-1917, xxviii,

211.

8. Hart and McCollum: Jour. Biol. Chem., 1914, xix, 373.
McCollum, Simmonds and Pitz : Ibid, 1916, xxviii, 153.

9. McCollum, E. V., Simmonds, N., and Parsons, H. T.:

Unpublished data.
10. McCollum, E. V. : Jour. Am. Med. Assn., 1917, kviii, 1379.
Harvey Lecture Series 1916-1917 — ^also — ^Unpublished
data.

BIBLIOGRAPHY 193

11. McCollum, Simmonds and Pitz: Jour. Biol. Chem., 1917,

xxix, 521.

12. McCollum, Simmonds and Pitz: Jour. Biol. Chem., 1917,

XXX, 13.

Chapter III

1. Slonaker, J. R.: Leland Stanford Junior University, Pub.

Univ. Series, 1912.

2. McCollum, Simmonds and Pitz : Jour. Biol. Chem., 1917,

XXX, 13.

3. McCollum, Simmonds and Pitz: Am. Jour. Physiol., 1916,

xUv, 333.

4. Eward, J. M.: Proc. Iowa Acad. Sci., 1915, xxii, 375.
6. Loeb, J.: The Dynamics of Living Matter, New York,

1906.
6. Howell, W. H.: Am. Jour. Physiol., 1899, ii, 47; 1902, vi,
181.

Chapter IV

1. McCollum, E. v.: Jour. Biol. Chem., 1914, xix, 323.

2. McCollum and Simmonds: Jour. Biol. Chem., 1917, xxxii,

347.

3. McCollum and Davis: Jour. Biol. Chem., 1915, xx, 415.

4. McCollum, Simmonds and Parsons: Unpublished data.

Chapter V

1. McCollum and Kennedy: Jour. Biol. Chem., 1916, xxiv,

491.

2. Osborne and Mendel: Jour. Biol. Chem., 1913, xvi, 431.

3. McCollum and Simmonds: Jour. Biol. Chem., 1917, xxxii,

347.

4. McCollum, Simmonds and Parsons: Unpublished data.

5. Herdlika, A.: Bulletin 34, Bureau of American Ethnology.

194 BIBLIOGRAPHY

6. Mori, M. : Jahrb. Kinderheilk, 1904, lix, 175.

7. Bloch, C. E. : Ugeskruft ftir Laeger, 1917, bodx, 349, cited

from Jour. Am. Med. Assn., 1917, Ixviii, 1516.

8. Czemy, A. and Keller, A. : Des Kindes, Leipsic, 1906, pt.

2,67.

9. Little, A. D. : Jour. Am. Med. Assn., 1912, Iviii, 20129.

10. Walcott, A. M.: Jour. Am. Med. Assii., 1915, Ixv, 2145.

11. Eijkman, C: Arch. f. Hyg., 1906, Iviii, 150.

Arch. Path. Anat., 1897, cxlviii, 523.

12. Funk, C: Lancet, London, 1911, ii, 1266.

13. Funk and Macallum: Jour. Biol. Chem., 1915, xxiii, 419.

14. Williams, R. R.: Jour. Biol. Chem., 1916, xxv, 437; 1916,

xxvi, 431; 1917, xxLx, 495.

15. Jackson, L., and Moore, J. J.: Jour. Infect. Dis., 1916, xix,

478.

16. McCollum and Pitz: Jour. Biol. Chem., 1917, xxxi, 229.

17. Hess, A. F.: Am. Jour. Dis. of Children, 1917, xiv, 337.

18. ^Goldberger, Joseph: Jour. Am. Med. Assn., 1916, Ixvi, 471.

19. Jobling, J. W., and Peterson, W.: Jour. Infect. Dis., 1916,

xviii, 501.

20. Thompson-MacFadden Commission, Siler, J. F., Garri-

son, P. E.,and McNeal, W. J.: Archiv. Int. Med. Oct.

1914, p. 453; Joum. Amer. Med. Assn. Sept. 26, 1914,
p. 1090.

21. Goldberger, Joseph: Public Health Reports, November 17,

1916, pp. 3159-3173.

22. Goldberger, Joseph: Public Health Reports, Nov. 12,

1915, p. 3.

23. Chittenden, R. H. , and Underbill, F. P. : Am. Jour. Physiol.,

1917, xliv, 13.

24. McCollum, Simmonds and Parsons: Jour. Biol. Chem.,

1918, xxxiii, 411.

25. McCollum and Simmonds: Jour. Biol. Chem., 1917,

xxxii, 29.

26. Hess, A. F. : Jour. Am. Med. Assn., 1918, bcx, 900..

BIBLIOGRAPHY 195

Chapter VI

1. McCollum and Simmonds: Am. Jour. Phjrs., 1918, xlvi,

275.
McCollum, Simmonds and Pitz: Jour. Biol. Chem., 1916,
xxvii, 33.

2. Osborne and Mendel: Jour. Biol. Chem., 1915, xx, 379.

3. Andrews, V. L.: Philippine Jour. Science, Series B, 1912,

vii,67.

4. Babcock, S. M.: Twenty-Second Annual Repk)rt of Wis-

consin Experiment Station, 1905, 129.

5. Eckles, C. H.,and Pahner, L. S.: Missouri Agric. Expt.

Station Research Bull., 25, 1916.

6. Ducaisne, E.: Gaz. Med., Paris, 1871, 317.

Chapter VII

1. Osborne and Mendel: Jour. Biol. Chem., 1915, xx, 381.

2. McCollum and Davis: Jour. Biol. Chem., 1915, xxiii, 247.

3. McCollum, Simmonds and Pitz: Jour. Biol. Chem., 1917,

xxix, 521.

4. Sullivan, M. X., and Voegtlin,C.: Jour. Biol. Chem., 1916,

xxiv, xvi.

5. Simpson and Edie : 1911-12, Ann. Trop. Med. and Parasit.,

V, 321.
Ohler: Jour. Med. Research, 1914, xxxi, 239.

6. Withers and Camith: Jour. Agric. Research, 1915, v, 261.

Jour. Biol. Chem., 1917, xxxii, 245.

7. McCollum and Davis: Jour. Biol. Chem., 1915, xxiii, 231.

8. McCollum and Simmonds: 1917, xxxii, 181,

INDEX

Alfalfa flour, 41, 167, 169, 179
Alkaloids, 4
Amino-acids, 5, 74, 75
Appetite, importance of in the
selection of food, 64

Barley, 38
Bean, navy, 38, 181
Bean, soy, 38, 175
Beri-beri, 7, 20, 28, 83, 90
Biological method for the anal-
ysis of food-stuffs, 20, 21, 56,
113, 161
Butter fat, 1^, 89

Camivora, dietary habits of, 78
Cereal grains, 157, 161
Chittenden and Underhill, stud-
ies of pellagra, 107
Corn, 10, 173
Cotton seed flour, 142, 143

Deficiency diseases, 83-87, 91
95, 114

Diet and disease, 6, 7

Diet, essential factors in, 31

Diet of nursing mother in rela-
tion to the quality of her
milk, 116-129, 185-189

Diet, planning of adequate, 130

Diet, monotonous, 7

Dietary essentials, nomencla-
ture of unidentified, 32

Dietary essentials, chemically

unidentified, 23, 34, 47
Dietary habits, 139
Diets from single plant sources,

10
Diets, simplified, 9, 14, 15, 16,

19, 155
Disease and diet, 6, 30, 36, 87,

95, 103, 139
Diseases, deficiency, 83-87, 91,

95, 114

Eggs, 80

Eijkman, 7

Eward, studies on appetite, 64

Fats, 2, 3, 4

Fats, butter, 16

Fats, egg yolk, 16

Fats, lard, 16

Fats, vegetable, 16

Fat-soluble A, 23, 34, 47, 89,

145, 155
Flax seed, 38
Food analysis, 5
Foods, effect of cooking on,

135-138
Foods, physical properties of,

15
Foods, protective, 82, 141, 147,

149
Foods-stuffs, biological analysis

of, 20, 21, 56

197

198

INDEX

Food-6tiiffs, supplementary re-
lationships among, 61, 71, 81
Eraser and Stanton, 19
Fruits, 7, 142
Funk, 19

Gelatin, 171

Glandular organs, 79

Gliadin, 8

Goldberger, studies of pellagra,

105-107
Growth, impetus to, 72

Henriques and Hansen, stud-
ies of simplified diets, 8
Hess, studies of scurvy, 100
Hoist, studies of sciurvy, 34
Hopkins, studies of simplified

diets, 18
Hormones, 85

Inorganic salts, importance of,

4,22
Iron, 69

Jobling and Peterson, studies
of pellagra, 105-106

Kafir com, 38

Leaf, dietary properties of, the,

41, 44, 53, 77
Leaf and seed mixtures, dietary

properties of, 61, 167
Lipoids, 3, 17

Meats, 6, 8, 76
Milk, 6, 8, 76

Milk, place of in the diet, 150-
153

Milk, production, 12

Milk, quality of, as influenced

by diet, 116-129, 18&-189
MiUet seed, 38, 175, 177
Muscle tissue, 6, 8, 76
Nomenclature of the chemically

unidentified dietary essentials,

Osborne and Mendel, 87

Pasteurization of milk, 100-103
Peanut, 142
Peas, 38, 177, 181
Pella^, 7, 30, 103
Pellagra-producing diets, 108
Polyneuritis, 19, 20, 28
Potato, protdns of, 135, 181
Proteins, 2, 3, 4, 5
Proteins, biological values of,

5, 24, 74, 75
Proteins, quality not shown by

chemical analysis, 113

Rat, domestic, 14

Rat, domestic, growth of, 14

Rat, reproduction in, 14

Rice, dietary properties of, 27,

38, 159, 161
Rickets, 111
Roots, edible, 47
Rye, dietary properties of, 38,

175

Salts, 4

Scurvy, 7, 30, 34, 36, 37, 95-103
Seed, biological properties of, 53
Seed, and leaf mixtures, dietary
properties of, 61

INDEX

199

Seeds, dietary properties of, 6,
165

Slonaker, studies of vegetarian
diet, 57

Smith, Theobald, scurvy in the
guinea pig, 34

Sodium, lack of sufficient, in
seeds, 23, 49

Starch, 2, 3, 4

Stepp, studies of dietary prop-
erties of lipoids, 17

Thompson-McFadden Commis-
sion, studies of pellagra, 106

Tubers, dietary properties of,
6,45

Variety not a safeguard in nutri-
tion, 66
Vegetable oils, 16
Vegetables, 6, 7
Vegetarian diet, 50, 53

Water, 4

Water-soluble B, 29, 34, 47,
155

Wheat and other cereals com-
pared, 139

Wheat, dietary properties of,
10, 20, 21, 38, 157, 159, 171,
175, 179

Wheat flour, bolted, 140

Wheat flour, whole, 140

Unidentified factors in the diet, Xerophthalmia of dietary origin,
17, 18 87, 139

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tastes at the same table are also taken up, as are the
cost of food and the construction of menus. A final
chapter deals with feeding the sick.

THE MACMILLAN COMPANY

Publishers 64-66 Fifth Avenue New York

War Bread

By ALONZO E. TAYLOR

Professor of Physiological Chemistry, University of Penn-
sylvania; member of the United States Food Admin-
istration ^ ^^

Dr. Taylor states that it is his pmpose to make clear
just what must be accomplished in order that we may
give to every member of the allied people his full share
in our pooled food stuflf at the lowest comparable cost
and with the least labor. With this in view, he takes up
the following topics:

What the Allies Need; What We Possess; Why We are
Limited in Wheat; Food Value of the Different Grains;
Ways of Stretching Wheat; and Waste of Wheat.

The Food Problem

By VERNON KELLOGG and ALONZO E. TAYLOR

With an Introduction by Herbert Hoover

tl£o

"Food," says Mr. Hoover in his introduction, "is
always a problem in every phase of its production, han-
dling, and consumption. It is a problem with every
farmer, every transporter and seller, every state and
nation. And now very conspicuously it is a problem with
three great groups; namely, the AlUes, the Central Em-
pires, and the Neutrals; in a word, it is a great inter-
national problem."

Some of the questions which the book considers in
detail are: What is the problem in detail? What are the
general conditions of its solution? What are the imme-
diate problems and particulars which concern us? and
finally. What are we actually doing to meet the problem?

THE MACMILLAN COMPANY

Publishers 64-^ Fifth Avenue New York

RETURN TO the circulation desk of any
University of California Library

or to the

NORTHERN REGIONAL LIBRARY FACILITY
BIdg. 400, Richmond Field Station
University of California
Richmond, CA 94804-4698

ALL BOOKS MAY BE RECALLED AFTER 7 DAYS

• 2-month loans may be renewed by calling
(510)642-6753

• 1 -year loans may be recharged by bringing
books to NRLF

• Renewals and recharges may be made
4 days prior to due date

DUE AS STAMPED BELOW
MAY 9 2007

DD20 12M 1-05

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Full text of "The newer knowledge of nutrition; the use of food for the preservation of vitality and health"

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